Systematic review: The reliability of indicators that may differentiate between suicidal, homicidal, and accidental sharp force wounds

Jason M. Chin¹, Stephanie Clayton², Stephen Cordner³, Gary Edmond⁴, Bethany Growns⁵, Kylie Hunter⁶, Bernard I’Ons⁷, Kristy A. Martire⁸, Gianni Ribeiro⁹, Stephanie Summerby¹⁰

1. College of Law, Australian National University
2. South Wales Health
3. The Victorian Institute of Forensic Medicine
4. Law & Justice, University of New South Wales
5. School of Psychology, Speech, and Hearing, University of Canterbury
6. National Health and Medical Research Council Clinical Trials Centre, University of Sydney
7. New South Wales Health
8. School of Psychology, University of New South Wales
9. Criminology, University of Southern Queensland
10. Office of the Chief Forensic Scientist, Victoria Police Forensic Services Department

Originally published on October 2, 2004 at:

https://doi.org/10.31222/osf.io/atu56

Abstract

This protocol aims to address two metaresearch questions: what do we know about the science underlying impactful legal decisions and how can we assess this evidence efficiently and accurately, such that it is usable for courts? To do so, this protocol describes our plan for a systematic review of the literature underlying whether there are reliable indicators of the manner of death in stab wound cases. Evidence of nature was recently found admissible at the High Court of Australia in Lang v The Queen. However, despite the High Court uncritically accepting this evidence, there has never been a systematic review that critically appraises the relevant literature. Beyond the review itself, we will fully document our process and all of the time-saving tools we rely on to provide knowledge about whether systematic reviews of this nature can be efficiently deployed in legal proceedings.

Full article

Introduction

Rationale

This systematic review will identify and synthesise research that examines indicators that may be used to distinguish between suicidal and homicidal sharp force wounds (e.g., presence of defensive injuries, anatomical site of the wound).¹ It will also preliminarily assess the quality of this research. Although our search strategy (see below) is focused on homicidal and suicidal wounds, we will also include literature we find about fatal accidental sharp force wounds and cases where the manner of death was undetermined. We do this to provide a more complete resource for users.

We have undertaken this review in response to expert opinion evidence admitted in a murder trial (R v Lang), where a forensic pathologist opined that a stab wound to the torso was more likely homicide than suicide.² The testimony and several factors advanced in favour of the opinion were supported by oral references to experience and research.³ This review is an attempt to determine what support there is in the biomedical research literature for the expert opinion in Lang regarding factors that may reliably distinguish between stab wounds that are self-inflicted or inflicted by others.

Moreover, the broader question of whether admissible expert opinion is supported by mainstream biomedical research might cast light on admissibility rules and legal practice. Specifically, there are ongoing discussions about whether forensic pathologists and medical examiners should be permitted to provide manner of death conclusions for legal proceedings (as opposed to only making such conclusions for statistical purposes, which has not attracted critique).⁴ In short, external commentators⁵ and forensic professionals⁶ have argued that manner of death determinations, in many cases, are not reliable enough to be presented in court. Some have also argued that these determinations go beyond the expertise of forensic medical practitioners and encroach on the role of the judge or jury (i.e., the factfinder).⁷ Therefore, a systematic review evaluating the research basis for manner of death determinations in sharp force wound cases may provide broader insights into the risks and benefits of forensic pathology in the legal system. As we discuss below, existing systematic reviews on this topic made no attempt to assess the quality of the underlying research.⁸

Finally, we aim to provide practical guidance about conducting systematic reviews for legal proceedings. To help assess the practicality of such work, we will conduct this review with time-saving tools and carefully document the time this review takes, as well as any hurdles we encounter.⁹ Indeed, and as discussed below, previous reviews in forensic pathology have noted challenges in reviewing the literature due to a lack of guidance¹⁰ and reporting standards.¹¹

Prior reviews of research on manner of death in sharp force injury cases

Preliminary searches found two systematic reviews of the relevant literature (Appendix A). First, De-Giorgio and colleagues performed a systematic review that included 78 articles (672 cases) describing purported suicidal sharp force injuries and 52 articles (2,670 cases) describing purported homicidal sharp force injuries.¹² Their review covered both English and non-English language articles. The review authors noted their efforts to review the literature were hindered by poor reporting:

the data available in the literature are often not detailed, clear, or homogenous enough to perform a meaningful comparison between different studies. Thus, it was not possible to identify one or more parameters that are sufficient for making an absolute differential diagnosis between suicide and homicide.’¹³

For example, only about a fifth of the cases provided the localisation of the injuries and their number.¹⁴

While De-Giorgio and colleagues were critical of the reporting of the articles included in their sample, they did not comment on other aspects that may increase risk of bias. For instance, they did not scrutinise or themselves provide any detail about how the manner of death was determined in the included cases (e.g., through eyewitness accounts, video footage). Considering that they set out to provide a critical analysis of the literature, this was surprising.

The second review is a scoping review performed by AlGheryafi and colleagues.¹⁵ This review included six studies because, unlike Di-Giorgio et al, it included only retrospective studies (excluding case reports and case series). This review also set out to be a critical review¹⁶ but did not appraise the methodology of included studies. Its conclusions about indicators of suicidal versus homicidal sharp force wounds were:

According to the results, these parameters ranged from being strongly predictive to less predictive, and no single parameter was conclusive in differentiating suicide from homicide. Some of the important predictors of the homicidal manner of death in sharp-force fatalities include clothing damage, presence of defense injuries, presence of injuries caused by another type of violence other than sharp-force, vertically oriented chest stabs, and sharp-force injuries in the head and back anatomical sites. Some of the important predictors of the suicidal manner of death in sharp-force fatalities include the presence of tentative injuries, sharp-force injuries to the wrist, and the presence of a suicide note […] the findings related to individual parameters should be integrated with findings related to other parameters and collectively the manner of death should be determined for a more accurate diagnosis of the manner of death.¹⁷

AlGheryafi and colleagues listed some limitations.¹⁸ This included heterogeneity in the included cases (i.e., variance in their factual circumstances) and the restrictiveness of their own search strategy.¹⁹

Both previous reviews were helpful in allowing us to identify a variety of research relevant to our research question (see Table 1). They include a spread of article types (case studies, case series, retrospective studies). These articles helped us develop our methodology, as described below.

Table 1. Known articles

Authors	Year	Title	Type	Note
AlGheryafi et al	2024	Differentiating suicide from homicide in sharp-force fatalities with stab and/or incised wounds: A scoping review	Scoping review	Not to be included in eventual review, but title includes useful keywords
Brunel et al	2010	Homicidal and suicidal sharp force fatalities: Autopsy parameters in relation to the manner of death	Retrospective study
De-Giorgio et al	2015	Suicidal or homicidal sharp force injuries? A review and critical analysis of the heterogeneity in the forensic literature	Systematic review	Not to be included in eventual review, but title includes useful keywords
Di Nunno	2001	Suicide by hara-kiri: a series of four cases	Case series
Ito et al	2009	Traumatic ventricular septal defect following a stab wound to the chest	Case study
Karlsson	1998	Homicidal and suicidal sharp force fatalities in Stockholm, Sweden. Orientation of entrance wounds in stabs gives information in the classification	Retrospective study
Racette et al	2008	Suicidal and homicidal sharp force injury: a 5-year retrospective comparative study of hesitation marks and defense wounds	Retrospective study
Schädler et al	2024	Singular stab wounds to the trunk: Is this suicidal or homicidal?	Retrospective study
Scolan et al	2004	Homicide-Suicide by Stabbing Study Over 10 Years in the Toulouse Region	Retrospective study
Terranova et al	2020	Criminological and Medico-legal Aspects in Homicidal and Suicidal Sharp Force Fatalities	Retrospective study
Thomsen et al	2020	Sharp Force Homicide in Denmark 1992–2016	Retrospective study
Von linde et al	2024	A Swedish nationwide forensic study of the manner of death in single stab injuries to the trunk	Retrospective study

See Appendix B for full citations to these articles

Objectives

Our primary objective is to systematically review and critically appraise the literature identifying indicators of fatal self versus other-inflicted (i.e., suicidal versus homicidal) sharp force wounds (including stabbed and incised wounds). If there is literature regarding accidental sharp force wounds, we will also include that research. Secondarily, we will describe other aspects of this literature, such as the proportion of case reports following reporting guidelines (e.g., CARE)²⁰ and the proportion of studies that are open access.

Methods

Overview of methodology and description of preliminary searches

We identified two prior systematic reviews (those reviewed above). These reviews helped reveal further articles within the present review’s scope (Table 1). We used these articles to refine the search strategy described below.

Transparency of this review

The final version of this protocol will be prospectively registered on the Open Science Framework. Our PRISMA-P checklist is openly available. Any data we extract from articles will also made openly available on the Open Science Framework. Deviations from this protocol will be explicitly acknowledged in the final manuscript. We did not seek ethics board approval because this is a review of existing research.

Eligibility criteria

Inclusion criteria: We will include case studies, case series, and retrospective studies of participants of any age and sex. The primary outcome of interest is whether the fatal wound(s) was or were inflicted by the person themself (i.e., suicidal), another party (i.e., homicidal), or by accident. As a result, we will only include articles that record a fatal outcome in which a determination of manner of death was attempted. We will also only include cases in which the cause of death appears to be a sharp force wound (including stabbed and incised injuries). We will not restrict based on date.

Exclusion criteria: We will exclude non-English language articles due to a lack of non-English language proficiency among the review team.

Search strategy and information sources

Review author JC designed the search strategy and will perform the search (Appendix A). We will search MEDLINE via Ovid, Scopus, and Web of Science with no date restriction. We will record the date of the search. JC will perform backwards and forwards citation analysis using SpiderCite. For articles that SpiderCite is not able to search, we will generate those citations manually. JC will also deduplicate the result using Endnote.

The search string was generated using reference articles from preliminary searches (Table 1) and the search strings of two prior systematic reviews (see Appendix A). An information specialist (KH) and subject matter specialists (BI, SC) helped in the design of the search.

In terms of grey literature, the authors will contact the mailing lists for the U.S. National Association of Medical Examiners and the Medicolegal Death Investigation Subcommittee of the Organization of Scientific Area Committees (OSAC) for Forensic Science.

Study records

Selection process

Search results (title and abstract) will be screened for eligibility by two authors independently. One review author (JC) will retrieve full-text articles. Two authors will screen full texts for inclusion. The forward and backwards citation search will be screened by one author (JC). Discrepancies will be recorded and resolved through discussion.

Data management

We will use Endnote to manage the library of articles. Data will be extracted into spreadsheets, which will be made openly available on the Open Science Framework.

Data collection process

A standardised form (initially piloted on five included studies) will be used for data extraction of characteristics of studies, key variables, outcomes, and risk of bias. Two review authors will independently extract and code these items, with discrepancies recorded and resolved through discussion.

Data items

We will record the following variables. Article-level variables will be recorded using a Google form. Case-level variables will be recorded in spreadsheets (one spreadsheet for case studies and one spreadsheet for articles describing multiple cases).

Article variables – general

Full name of corresponding author
DOI
Article title
Year of publication
Journal title
Country of corresponding author
Email address of the corresponding author
Affiliations of all authors (e.g., university, law enforcement) – select all that apply
Type of article (case study, case series, retrospective study, systematic review)

Article variables – transparency and openness

Data available and, if so, where?
Code available and, if so, where?
Prospectively registered and if so where?
Purports to follow a reporting guideline (e.g., CARE)?
Open access with publisher (gold open access)?
Open access elsewhere (i.e., green open access) (e.g., ResearchGate)?
Funding sources declared or no statement
Conflicts of interest declared or no statement

Case(s) – Background variables

Number of cases
Date or date range of included cases (or for each case if reported individually)
Geographic location of cases (as specific as possible, City, State, Nation)
Reported gender/sex of deceased (for each case if reported individually)
Age of deceased (for each case if reported indivdually)
Was there a formal recording of the death scene by a forensic pathologist or medical examiner? (for each case if reported indivdually)

Case(s) – Focal Injury/Injuries

Number of wounds
Type of wound (for each wound)
- If bone or cartilage wounds, method of determining this (visual, VT, Xray)
Site of wound (for each wound)
Orientation of wound (for each wound)
Severity of wound (for each wound)
- Using Injury severity score
Track marks within single wound? (for each wound)
Turn and reinsertion? (for each wound)

Case(s) – Other injury/injuries (number, location, healing/fresh)

Hesitation/tentative injuries and description (for each case if reported individually)
Defensive injuries and description (for each case if reported individually)
Bruises and description (for each case if reported individually)
Lacerations and description (for each case if reported individually)
Abrasions and description (for each case if reported individually)
Other (e.g., post mortem injuries, associated injuries, including petechiae in neck compression cases which might have occurred alongside the sharp force injury)

Case(s) – Other variables

Toxicology (for each case if reported individually)
Psychiatric history, including source of history (e.g., deceased’s general practitioner) (for each case if reported individually)
Other pre-existing illnesses (for each case if reported individually)
Damage to clothing (for each case if reported individually)
Suicide note (for each case if reported individually)
Weapon found (for each case if reported individually)
- Weapon type (if found)

Risk of Bias

Risk of bias will be assessed as described below.

Overall quality of evidence

Overall quality of evidence will be assessed as described below.

Outcomes and prioritization

The primary outcome we will assess is the conclusion that the fatal wound(s) were homicidal or suicidal.

Data synthesis – Exploratory

We will attempt to quantitively synthesise cases by first separating them into four groups: those classified by study authors as suicides, homicides, accidents or inconclusives.²¹ Then, we will list the frequency with which the case variables listed above appear in each group. If we calculate a percentage for that variable, we will calculate that against the number of cases in which the authors specifically stated whether the variable was measured (e.g., the proportion of suicides with positive toxicology results will be calculated only on cases where it is explicitly stated that toxicology was taken). We may also provide separate tables for studies with high versus low risk of bias. The quantitative synthesis should be considered exploratory.

We will also perform article-level quantitative summaries, such as the frequency and percentage of that articles that are open access. For quantitative syntheses, we may apply a measure of uncertainty, such as confidence intervals.

Again, any conclusions drawn from this synthesis should be treated with caution and considered exploratory. This is because there is no existing guidance on meta-analysis for the type of research included in this review. Much of our analysis will be contingent on the data we can extract and the quality of that data, both of which are difficult to forecast.

Risk of bias assessment – exploratory

We will adapt existing risk-of-bias tools²² used for assessing medical interventions because we are not aware of any tools designed for forensic pathology. Indeed, in an earlier systematic review of the suicidal strangulation literature, Cordner and colleagues remarked on this lacuna: ‘As far as we are aware there is no critical appraisal instrument available to determine the quality of a medico-legal death investigation as presented in a case report’.²³ To begin to develop such an instrument, we identified three items from Cochrane’s risk of bias approach and tool,²⁴ and will adapted them. However, we may also develop other methods once we have read and reviewed the literature we identify.

First, we can adapt two sources of bias from Cochrane’s ‘information bias’²⁵ category. Cochrane notes that information biases (also referred to as measurement bias) can occur when intervention:

cases may be more likely than controls to recall potentially important events or report exposure to risk factors they believe to be responsible for their disease. Differential misclassification of intervention status can occur in cohort studies if it is obtained retrospectively. This can happen if information (or availability of information) on intervention status is influenced by outcomes: for example a cohort study in elderly people in which the outcome is dementia, and participants’ recall of past intervention status at study inception was affected by pre-existing mild cognitive impairment.²⁶

In manner of death cases, some indicators may be recorded differently or only be recorded in cases where homicide or suicide is expected. Accordingly, studies should take steps to engage in some blinding or systematization when recording indicators of homicide or suicide (e.g., an author unaware of the determination is in charge of collecting and quantifying information about the number of wounds and their severity or there are standard items to record).

Another source of information bias is bias in the measurement of the outcome. For instance, there is a risk of circularity: indicators manners of death are taken to be reliable because they were used to determine manner of death in included cases. As a result, some independent and relatively objective assessment of ground truth is preferable. A priori, we can only speculate as to the safeguards studies may put into place. Therefore, bias in the measurement of the outcome will be done after assessing the included studies. Before fully viewing the literature, we can speculate that risk of bias may vary, with some cases including very clear manners of death (e.g., the deceased is found in a room locked from the inside or the death is viewed by several eyewitnesses) or very unclear manners of death (e.g., the manner of death is determined based on the same indicators recorded in the case).

Note that in their systematic review of shaken baby research, Lynøe et al used a similar approach:

Studies were assessed as having a low risk of bias when the study cases, namely shaken babies, were unequivocally confirmed as having been violently shaken and when the shaking preceded the symptoms associated with the triad, for example by a video recording or independent witness information. […] Studies were assessed as having a moderate risk of bias when the shaken baby study cases were identified as the result of a detailed confession by the suspected perpetrator…²⁷

Finally, both observational studies and randomised trials are at risk of reporting biases.²⁸ For instance, Cochrane notes that ‘it is difficult to imagine that [reporting biases] are any less serious’²⁹ for observational studies because many observational studies ‘do not have written protocols, and many are exploratory so – by design – involve inspecting many associations between intervention and outcome’.³⁰ A major way in which reporting biases are assessed is considering ‘Whether the trial was analysed in accordance with a pre-specified plan that was finalized before unblinded outcome data were available for analysis’. Accordingly, when available, we will record any divergences between pre-specified plans and the ultimate reporting. If the prespecified plan is not available, we will note this. We will also note whether articles purported to follow a reporting guideline (e.g., CARE).

To summarise, we will assess:

Blinding
Ground truth assessment
Methods to control reporting biases

Using our assessment on those three criteria, we will provide a holistic risk of bias judgment for each article based on the levels of risk of bias in ROBINS-I.³¹ Once again, given the lack of work in this area, this should be considered exploratory. Two members of the review teams will make these assessments independently, with disagreements adjudicated by discussion.

Confidence in cumulative evidence – exploratory

We will adapt GRADE (Grading of Recommendations, Assessment, Development, and Evaluation)³² to provide an estimate of the general level of confidence in the evidence that there are reliable indicators of suicidal and homicidal sharp force wounds. GRADE consists of five factors: limits in study design or execution (risk of bias), inconsistency of results, indirectness of evidence, imprecision, and publication bias. Not all of these factors are applicable or will be easy to estimate concerning our research question and literature. However, we will be able to provide an assessment of the following factors:

Study design by appraising the included studies as a whole by providing a holistic synthesis of the individual risk of bias assessments of included studies.
Imprecision by considering the total number of included cases and associated measures of uncertainty (e.g., confidence intervals).

Two review authors will make these determinations independently and resolve disagreements through discussion. As with risk of bias, our confidence in cumulative evidence assessment should be considered exploratory due to the lack of existing guidance and protocols for this determination in forensic pathology. We will also provide comments and discussion about any other overall strengths and limits in the found literature.

Notes

‘Commonly used characteristics for differentiation between self-inflicted and third-party-inflicted injuries are the anatomical site, the number and arrangement of injuries, damage of clothing, the presence of hesitation or defense wounds, and the direction of the stabbing wound canal.’: Julia Schädler et al, ‘Singular stab wounds to the trunk: Is this suicidal or homicidal?’ (2024) 68 Legal Medicine 102430.
Lang v The Queen [2023] HCA 29.
Ibid [21], [456], [466].
Note that such practices vary by jurisdiction.
Dan Simon, ‘Minimizing Error and Bias in Death Investigations’ (2019) 49 Seton Hall Law Review 255; Keith A Findley and Dean A Strang, ‘Ending Manner-of-Death Testimony and Other Opinion Determinations of Crime’ (2022) 60 Duquesne Law Review 302.
William Oliver et al, ‘Cognitive Bias in Medicolegal Death Investigation’ (2015) 5(4) Academic Forensic Pathology 548, 552 ‘it is a matter of weighing information for which there may not be much certainty’; William R Oliver, Manner Determination in Forensic Pathology (2014) 4(4) Academic Forensic Pathology 480.
Findley and Strang (n 5).
Systematic reviews that seek to appraise quality appear to be rare, see Stephen Cordner et al, ‘Suicidal ligature strangulation: a systematic review of the published literature’ (2020) 16 Forensic Science, Medicine and Pathology 123, 130: ‘As far as we are aware there is no critical appraisal instrument available to determine the quality of a medico-legal death investigation as presented in a case report.’; However, we are aware of one attempt to adapt an existing appraisal tool: Niels Lynøe et al, ‘Insufficient evidence for ‘shaken baby syndrome’ – a systematic review’ (2017) 106 Acta Pædiatrica 1021, 1023.
Justin Clark et al ‘A full systematic review was completed in 2 weeks using automation tools: a case study’ (2020) 121 Journal of Clinical Epidemiology 81.
Cordner et al (n 8).
Fabio De-Giogio et al, ‘Suicidal or Homicidal Sharp Force Injuries? A Review and Critical Analysis of the Heterogeneity in the Forensic Literature’ (2015) 60(S1) Journal of Forensic Sciences S97, S105: ‘Nevertheless, the data available in the literature are often not detailed, clear, or homogenous enough to perform a meaningful comparison between different studies. Thus, it was not possible to identify one or more parameters that are sufficient for making an absolute differential diagnosis between suicide and homicide.’.
Ibid.
Ibid S105.
Ibid S100.
Zainab Fathi AlGheryafi et al, ‘Differentiating suicide from homicide in sharp-force fatalities with stab and/or incised wounds: A scoping review’ (2024) 67 Legal Medicine 102388.
Ibid 3.
Ibid 8 [emphasis added].
Ibid 8.
Ibid 8.
https://www.care-statement.org/.
See Table 5 in Thore Karlsson, ‘Homicidal and suicidal sharp force fatalities in Stockholm, Sweden. Orientation of entrance wounds in stabs gives information in the classification’ (1998) 93 Forensic Science International 21, 28.
Jonathan AC Sterne, ‘RoB 2: a revised tool for assessing risk of bias in randomised trials’ (2019) 366 BMJ l4898; Jonathan AC Sterne et al, ‘ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions’ (2016) 355 BMJ i4919.
Cordner et al (n 8) 130.
Julian PT Higgins, Cochrane Handbook for Systematic Reviews of Interventions (version 6,3, 2023) Cochrane. https://training.cochrane.org/handbook.
Ibid 25-2.
Ibid 25-2-3.
Lynøe et al (n 8) 23.
Ibid 25-2-4.
Ibid 25-2-4.
Ibid 25-2-4.
Sterne et al (n 22).
Gordon Guyatt et al, ‘GRADE guidelines: 1. Introduction – GRADE evidence profiles and summary of findings tables’ (2011) 64 Journal of Clinical Epidemiology 383.

Appendix A. Background on search strategy development

This appendix provides some background on how we developed our search strategy. In particular, we built off the strategies used by two previous systematic reviews: AlGheryafi et al and De-Giorgio et al.

AlGheryafi et al

AlGheryafi et al used the following search string:

(“suicide”[Title] OR “suicidal”[Title] OR “self harm”[Title] OR “self”[Title] OR “self injury”[Title]) AND (“homicide”[Title] OR “homicidal”[Title] OR “kill”[Title] OR “murder”[Title]) AND (“stab wound”[Title] OR “stab injury”[Title] OR “stab injuries”[Title] OR “stabbing”[Title] OR “incised wound”[Title] OR “incised injuries”[Title] OR “cut”[Title] OR “sharp wound”[Title] OR “sharp injury”[Title] OR “sharp injuries”[Title] OR “knife”[Title] OR “thrust”[Title] OR “sharp weapon”[Title] OR “scalpel”[Title] OR “sharp force”[Title])

This returns 25 articles as of July 24, 2024 (consistent with their reporting of 23) and catches 5/10 of the reference articles in Table 1. A major limitation is the lack of root expanders (e.g., substituting stab wound* for stab wounds would catch an additional article) and a lack of the term ‘manner’.

De-Giorgio et al

De-Giorgio et al conducted two searches (in Medline), one for homicides and one for suicides.

Suicides

stab wound* OR stab injur* OR cut wound* OR cut injur* OR sharp injur* OR sharp wound* AND suicid*

Homicides

(stab wound* OR stab injur* OR cut wound* OR cut injur* OR sharp injur* OR sharp wound* AND murder) OR (stab wound* OR stab injur* OR cut wound* OR cut injur* OR sharp injur* OR sharp wound* AND murder*) OR (stab wound* OR stab injur* OR cut wound* OR cut injur* OR sharp injur* OR sharp wound* AND homicid*)

These are helpful, but appear to be missing some notation (quotation marks and parentheses).

This review’s search strategy

We combined many of the terms in these searches with keywords identified in our reference set using the WordFreq tool (https://sr-accelerator.com/#/wordfreq). We refined the search string using the SearchRefinery tool (https://sr-accelerator.com/#/searchrefinery), which helps identify terms that increase the total number of search results without finding relevant citations. The result of the process is the following search string (PubMed):

(suicid*[tiab] OR “self harm*”[ti] OR “self inflict*”[ti] OR “self injury”[ti] OR herself[tiab] OR himself[tiab] OR homicid*[tiab] OR murder*[tiab] OR kill[ti] OR manner[ti] OR assault[tiab] OR accident*[tiab]) AND (“sharp force”[tiab] OR “sharp wound*”[tiab] OR “sharp injur*”[tiab] OR “sharp weapon”[ti] OR stab[tiab] OR “stab wound*”[tiab] OR stabbing[tiab] OR stabbed[tiab] OR “stab injur*”[tiab] OR “cut wound*”[tiab] OR cutting[ti] OR “cut injur*”[tiab] OR incis*[ti] OR knife[ti] OR scalpel[ti])

This results in 1587 total PubMed results on September 27, 2024, finding 10/10 reference articles.

We will search MEDLINE via Ovid, Scopus, and Web of Science. Those strings have been generated based the above PubMed string using Polyglot (https://sr-accelerator.com/#/polyglot):

MEDLINE via Ovid

(suicid*.tw. OR “self harm*”.ti. OR “self inflict*”.ti. OR “self injury”.ti. OR herself.tw. OR himself.tw. OR homicid*.tw. OR murder*.tw. OR kill.ti. OR manner.ti. OR assault.tw. OR accident*.tw.) AND (“sharp force”.tw. OR “sharp wound*”.tw. OR “sharp injur*”.tw. OR “sharp weapon”.ti. OR stab.tw. OR “stab wound*”.tw. OR stabbing.tw. OR stabbed.tw. OR “stab injur*”.tw. OR “cut wound*”.tw. OR cutting.ti. OR “cut injur*”.tw. OR incis*.ti. OR knife.ti. OR scalpel.ti.)

Scopus

(TITLE-ABS(suicid*) OR TITLE(“self harm*”) OR TITLE(“self inflict*”) OR TITLE(“self injury”) OR TITLE-ABS(herself) OR TITLE-ABS(himself) OR TITLE-ABS(homicid*) OR TITLE-ABS(murder*) OR TITLE(kill) OR TITLE(manner) OR TITLE-ABS(assault) OR TITLE-ABS(accident*)) AND (TITLE-ABS(“sharp force”) OR TITLE-ABS(“sharp wound*”) OR TITLE-ABS(“sharp injur*”) OR TITLE(“sharp weapon”) OR TITLE-ABS(stab) OR TITLE-ABS(“stab wound*”) OR TITLE-ABS(stabbing) OR TITLE-ABS(stabbed) OR TITLE-ABS(“stab injur*”) OR TITLE-ABS(“cut wound*”) OR TITLE(cutting) OR TITLE-ABS(“cut injur*”) OR TITLE(incis*) OR TITLE(knife) OR TITLE(scalpel))

Web of Science

((TI=suicid* OR AB=suicid*) OR TI=”self harm*” OR TI=”self inflict*” OR TI=”self injury” OR (TI=herself OR AB=herself) OR (TI=himself OR AB=himself) OR (TI=homicid* OR AB=homicid*) OR (TI=murder* OR AB=murder*) OR TI=kill OR TI=manner OR (TI=assault OR AB=assault) OR (TI=accident* OR AB=accident*)) AND ((TI=”sharp force” OR AB=”sharp force”) OR (TI=”sharp wound*” OR AB=”sharp wound*”) OR (TI=”sharp injur*” OR AB=”sharp injur*”) OR TI=”sharp weapon” OR (TI=stab OR AB=stab) OR (TI=”stab wound*” OR AB=”stab wound*”) OR (TI=stabbing OR AB=stabbing) OR (TI=stabbed OR AB=stabbed) OR (TI=”stab injur*” OR AB=”stab injur*”) OR (TI=”cut wound*” OR AB=”cut wound*”) OR TI=cutting OR (TI=”cut injur*” OR AB=”cut injur*”) OR TI=incis* OR TI=knife OR TI=scalpel)

Appendix B. Citation information for Table 1

Zainab Fathi AlGheryafi et al, ‘Differentiating suicide from homicide in sharp-force fatalities with stab and/or incised wounds: A scoping review’ (2024) 67 Legal Medicine 102388.
Christophe Brunel et al,, ‘Homicidal and suicidal sharp force fatalities: Autopsy parameters in relation to the manner of death’ (2010) Forensic Science International 150.
Fabio De-Giogio et al, ‘Suicidal or Homicidal Sharp Force Injuries? A Review and Critical Analysis of the Heterogeneity in the Forensic Literature’ (2015) 60(S1) Journal of Forensic Sciences S97.
Nunzio Di Nunno et al, ‘Suicide by Hara-kiri’ (2001) 22(1) The American Journal of Forensic Medicine and Pathology 68.
Hideki Ito et al, ‘Traumatic ventricular septal defect following a stab wound to the chest’ (2009) 57 General Thoracic and Cardiovascular Surgery 148.
Thore Karlsson, ‘Homicidal and suicidal sharp force fatalities in Stockholm, Sweden. Orientation of entrance wounds in stabs gives information in the classification’ (1998) 93 Forensic Science International 21.
Stéphanie Racette ‘Suicidal and homicidal sharp force injury: a 5-year retrospective comparative study of hesitation marks and defense wounds’ (2008) 4 Forensic Science, Medicine, and Pathology 221.
Julia Schädler et al, ‘Singular stab wounds to the trunk: Is this suicidal or homicidal?’ (2024) 68 Legal Medicine 102430.
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CRediT Statement

Conceptualization: Jason M. Chin, Stephanie Clayton, Stephen Cordner, Gary Edmond, Bethany Growns, Kylie Hunter, Bernard I’Ons, Kristy A. Martire, Gianni Ribeiro, and Stephanie Summersby.

Methodology: Jason M. Chin, Stephanie Clayton, Stephen Cordner, Gary Edmond, Kylie Hunter, Bernard I’Ons, Gianni Ribeiro, and Stephanie Summersby.

Project administration: Jason M. Chin.

Writing – original draft: Jason M. Chin.

Writing – review & editing: Jason M. Chin, Stephanie Clayton, Stephen Cordner, Gary Edmond, Bethany Growns, Kylie Hunter, Bernard I’Ons, Kristy A. Martire, Gianni Ribeiro, and Stephanie Summersby.

Guarantor of review: Jason M. Chin

Editors

Ludo Waltman
Editor-in-Chief

Jennifer Anne Byrne
Handling Editor

Editorial Assessment

by Jennifer Anne Byrne

DOI: 10.70744/MetaROR.23.1.ea

This protocol aims to address two questions: (1) What do we know about the science underlying impactful legal decisions? (2) How can we assess this evidence efficiently and accurately, such that it is usable for courts? The protocol has been reviewed by three reviewers (reviewer 2 in fact represents a team of three individuals). The reviewers mention various strengths of the protocol. Reviewer 1 emphasises the importance and timeliness of the research questions and praises the interdisciplinary nature of the research team. Reviewer 3 considers the protocol to be thoughtful and detailed, and reviewer 2 notes that the protocol presages an important effort. The reviewers do not see any major shortcomings in the protocol, but they do highlight opportunities to strengthen the protocol, such as considering studies published in languages other than English and adding more detail on how team disagreements will be resolved.

Competing interests: Jennifer Byrne is a member of the editorial team of MetaROR working with Jason Chin, a co-author of the protocol and also a member of the editorial team of MetaROR.

Peer Review 1

Alex Biedermann

DOI: 10.70744/MetaROR.23.1.rv1

Summary

This protocol describes the plan for a systematic review of the literature on stab wounds. The focus is on the types of observations made in such cases, and whether there are any (types of) observations that can be considered “indicators” of the manner of death, to help distinguish between cases of self-inflicted injury and those inflicted by others.

Strong points of this research plan

The authors present compelling arguments for the need for the proposed meta-research project; they refer to a recent case in the High Court of Australia (Lang v the Queen). The arguments highlight the importance and timeliness of the research questions. More generally, the field of forensic pathology and its perception and use by the legal community seems to be an area with great research potential: see for example the problematic cases involving the testimony of Colin Manock in South Australia (e.g. the Keogh case, where the examination of bruises was an issue).

Overall, the research plan is well informed: the authors have conducted a preliminary review of existing relevant studies and reviews. They use the findings from this preliminary review to critically inform the design of their study.

The research team is interdisciplinary, with members from law, psychology and pathology, and appears to be suitably qualified to carry out the proposed research.

The research plan is sufficiently detailed and transparent in terms of search procedures, eligibility criteria, outcome variables, data management and open access policy, which should make the research results widely accessible and reproducible.

Comments, suggestions, critiques

The title includes the term “reliability”, but it is never defined in the text. While this term can be taken in its common sense interpretation, this may not be sufficient for a scientific study. Do the authors mean “reliability” as used, for example, by the US FRE? Or do they understand the term to be similar to the PCAST’s use of the term “validity”?

The plan is not clear (enough) about how – conceptually – to characterise the potential of an observation (made by a pathologist) to provide information about a selected question of interest (e.g., manner of death, the way in which an injury was inflicted, etc.). Formally, the diagnosticity of an observation (or type of observation) is defined in terms of a likelihood ratio. In other words, for an observation to have diagnostic value with respect to a given proposition (hypothesis), the probability of the observation of interest given the proposition of interest must be higher than given an alternative proposition. Thus, whatever this study will reveal about medico-legal observations (in stab wound cases), an inferential framework is needed to assess diagnosticity and, more broadly, reliability. The research plan is silent on this aspect. Instead, most of the effort is spent on descriptive statistics. There is nothing wrong with descriptive statistics, but it will not help to address the main question posed in the title of the proposed research. As an aside, the reference to “confidence intervals” (p. 15 and 19) is unfortunate in the sense that frequentist statistics, although (still) ubiquitous, are problematic for a variety of reasons.

To some extent, the research proposal is too uncritical and passive with respect to terminology that appears to be standard in the field in which the literature review is to be conducted. Consider, for example, the terms “defense injuries” and “tentative injuries” (p. 7). These terms are problematic because they mix observations (e.g., cuts) with ground truth (i.e., self-inflicted or third-party inflicted). Since the ground truth cannot be known in actual cases, “defense injury” cannot meaningfully serve as a descriptor. Moreover, the use of such terms is problematic: suppose an examiner talks about “tentative injuries”. This could suggest to the recipient of expert information that the observed injury is necessarily self-inflicted. Of course, the authors’ intention might be to determine how diagnostic the expert’s utterance of “tentative injury” is with respect to the proposition of self-inflicted injury (without assuming that the utterance of “tentative injury” necessarily implies self-inflicted injury). Nevertheless, this doesn’t solve the problem of confusing terminology. Therefore, this research project could be strengthened by not limiting itself to the descriptiveadoption of standard terminology, but by including a critical analysis and discussion of terminology. In fact, the problem of testimony in this field is not limited to the (currently unknown) diagnosticity of observations made during pathological examinations. It also depends on the coherence of foundational terminology (i.e., its logic) used in this field, as well as on the soundness of the reasoning methods used (e.g., the crucial distinction between findings/observations and unobservable ground truth states).

On p. 15, the research plan states: “We will attempt to quantitively synthesise cases by first separating them into four groups: those classified by study authors as suicides, homicides, accidents or inconclusives. Then, we will list the frequency with which the case variables listed above appear in each group.” Treating the data in this way will lead to useful statistics: i.e., the probability of different observations given different case types (suicides, homicides, etc.). Such statistics characterise the diagnosticity of the various observations (“case variables”). However, a major problem arises here: how – if at all – it can one known that the reported classification of cases into suicides, homicides etc. was correct? For obvious reasons, none of the case reports in the literature involve experiments under controlled conditions. However, there may be other information or evidence in a case (e.g., video surveillance) that supports particular classifications. Will the project control for this complication, and if so, how?

It would be valuable for this research to include normative considerations, as opposed to a purely descriptive perspective, of what it means for an observation – be it in pathology or any other forensic field – to be “indicative” or discriminative with respect to selected (disputed) propositions. This relates to the notion of inferential frameworkmentioned above, which is largely established in the philosophy of science (see e.g. Howson/Urbach, Scientific Reasoning, 2005), and which could serve as an additional reference point against which to evaluate the current literature. It remains unclear to the reader why this research project refrains from taking a firmer position on the logic of evaluative thinking, which has now become inseparable from sound evaluation procedures in forensic science. Reviewing and synthesising existing literature is one thing, challenging the current state of the art is another. Combining the two is a valuable opportunity that this project could seize.

Competing interests: I declare that this review has been written in the absence of any competing interest, including any role, relationship (including commercial or financial) or commitment that poses an actual or perceived threat to the integrity or independence of my review and that could be construed as a potential conflict of interest.

Peer Review 2

Anonymous User

DOI: 10.70744/MetaROR.23.1.rv2

On behalf of the Center for Integrity in Forensic Sciences and its Executive Director, Katherine H. Judson, as well as its co-founder, Professor Emeritus Keith A. Findley, I am pleased to submit these comments on the above-cited draft work of Jason Chin, Stephanie Clayton, and their colleagues. Thank you for soliciting our views. You may learn more about the Center for Integrity in Forensic Sciences at http://www.cifsjustice.org

The authors’ explanation of their planned systematic review is helpful and presages an important effort. We commend the authors for their thoughtful study design, their transparency, and their initial research into source materials listed in Appendix A.

Two minor methodological concerns appear to us initially. One, we do not fully understand the intention, described in four places (pages 11, 18, and 19), to use two independent reviewers of data and to resolve disagreements “by discussion.” It is not clear whether that discussion is to occur between the pair of reviewers only, or whether others will join the adjudicative discussion. In either event, it may be useful to consider an odd number of adjudicators for purposes of breaking a deadlock, if necessary. Two, the intended systematic review excludes studies not published in English (see page 10). While the lack of proficiency in other languages among the research team is understandable (and rightly acknowledged), the availability of reliable translations today should allow inclusion of studies published in other languages, we suspect.

Our two principal substantive concerns are broader, though. First, this systematic review appears to overlook risks of availability bias and confirmation bias in information gathering by pathologists, who often rely on information passed along by law enforcement officers and others invested in a particular outcome or conclusion. Relatedly, forensic pathologists themselves often are closely aligned professionally and attitudinally with law enforcement personnel. Indeed, the pathologists may be employed by prosecutive and investigative agencies of the government, and therefore professionally and financially dependent on their sources of information. We predict that the research team will encounter frequently—perhaps almost uniformly—the absence of pre-existing protocols that Cochrane raises as a concern and that the authors rightly note at page 18 of this draft. That common absence of a known protocol, established in advance and subject to compliance assessment later, may be both caused in part by and an effect of the availability and confirmation (or tunnel vision) biases we discuss here.

Second, the systematic review does not seem designed to consider the normative question of which systemic actor or actors are best equipped and most appropriate to make manner of death determinations for judicial, as opposed to statistical, purposes. We hope that the researchers will recommend that such determinations by pathologists or other biomedical experts should be limited to statistical purposes, for use in allocating public

resources. In the end, regardless how reliable their opinions, pathologists and biomedical practitioners are no better positioned than jurors or judges to make adjudicative determinations of suicide or homicide, as the factfinders in a judicial system should have access to all information—presented to them in a more transparent, testable form in court—that the pathologist has in drawing conclusions. And as a normative matter, those adjudicative conclusions are assigned to jurors and judges, not to pathologists or other biomedical experts.

With these caveats, we again welcome this initial work and description of the metaanalysis to come. Especially if confined to assessing and advancing the reliability of manner of death determinations in cases of sharp force wounds for statistical purposes, and thus as an aid in allocating public resources outside the judicial system, the eventual systematic review may be quite valuable.

Finally, for a pertinent and longer discussion of related issues, see Keith A. Findley & Dean A. Strang, Ending Manner of Death Testimony and Other Opinion Determinations of Crime, 60 Duquesne Law Review 302 (2022). The authors themselves cite this article at footnotes 5 and 7 of their draft. Again, thank you for the opportunity to offer these comments.

Competing interests: None.

Peer Review 3

Miranda Cumpston

DOI: 10.70744/MetaROR.23.1.rv3

Thank you for the opportunity to review this protocol. My expertise is in systematic review methods, generally relating to health interventions, and as such I should note that I do not have expertise in forensic pathology or medico-legal issues.

This paper outlines the protocol for a systematic review of characteristics which allow forensic experts to distinguish between suicide and homicide relating to sharp force wounds, in the context of contributing to criminal prosecution. Interestingly, the protocol outlines the development of preliminary approaches to novel methodology adapted for use in this field, including novel approaches to assessing risk of bias and certainty in the evidence, which have primarily been developed to assess intervention research.

I commend the authors for a thoughtful and detailed protocol. In my view, this is a strong piece of work and will contribute findings of interest to the field, as well as contributing to the exploration of methods for the assessment of a category of research for which such methods are currently lacking. I have made a few suggestions below for consideration by the authors that may strengthen the protocol.

Rationale

It may be helpful to international readers to clarify in the text of the Rationale that R v Lang is a case in the High Court of Australia, and to spell HCA out in full in the footnote. With regard to readers looking for details on this case, are these published on a website for which a URL can be provided?
It would be helpful for readers without a background in legal proceedings to discuss the extent to which research evidence and systematic reviews are or are not commonly presented in legal proceedings, in contrast to expert opinion.
Where you discuss the debate about the role of cause of death findings, it would be helpful to explicitly state in which jurisdictions these discussions have been occurred, so that readers can understand whether and how this topic relates to their own jurisdiction or where there may be differences. It may further be helpful to elaborate briefly on why cause of death determinations may be considered unreliable.

Methods

It is a limitation to the review to only include studies published in English. The proficiency of automated translation is currently such that screening of potentially relevant studies in multiple languages is often possible, with assistance from multilingual colleagues or communities such as Cochrane Engage can enable the inclusion of studies in additional languages.
Regarding grey literature, both of the listed organisations appear to be based in the USA (although this is not stated for the OSCAC) – could you provide a rationale for only using US institutions to identify relevant data? For example, there may be organisations in Australia (which is the jurisdiction of interest for the legal aspects of this review) or in countries with comparable criminal legal systems (such as the UK, Europe or elsewhere).
Will a software tool be used to support study selection, such as Covidence or similar? This may contribute to your analysis of time and process.
Injury severity score – will injury severity be captured if other measures of severity are used, or not at all? There are methods available to consider results across different measures of similar outcomes, if these would be considered valid alternatives.
· In the rationale and the methods relating to risk of bias, you note that it may be relevant to capture (if available) information such as whether witness, video evidence or a confession was available to support the conclusion of cause of death. Should this kind of characteristic be added to the data collected?
The methods provided for data synthesis, risk of bias assessment and the certainty/quality of the evidence (based on GRADE) all currently read as if all your included studies will be case series or case studies. As your included studies also include observational studies that may give effect estimates such as odds ratios rather than individual counts of characteristics, methods should be provided for handling and perhaps quantitatively synthesising this kind of data, where appropriate. Risk of bias methods and GRADE methods may more closely correspond to the existing methods for this kind of study, and require less adaptation.
GRADE methodology generally refers to “certainty in the evidence” rather than confidence, to avoid confusion with risk of bias assessment.
You note in the rationale that you plan to collect data on the review process, such as time taken to complete different tasks. I’d suggest putting this detail in the methods section.
I would recommend giving some further thought to how you will draw conclusions from the data you find int his review. Assuming that sufficient data can be found, and that you have a set of either percentages from case studies/series or effect estimates from observational studies, it is likely that you will wish to discuss which factors appear to be associated with different causes of death, or which are most effective at discriminating between causes. I would strongly recommend considering what thresholds for associations or differences between causes of death would underpin such conclusions, and specify these in advance. I’d recommend speaking to a statistician to draft these methods appropriately and avoid errors in interpreting the estimates found.

Competing interests: None.

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