Homicide by Hanging: a Comprehensive Review of Published Literature

Homicide by hanging is a rare incident and, in contrast to suicidal hanging cases, only limited number of homicidal hanging cases have been reported. This comprehensive review is conducted to summarize the published forensic pathology evidence in homicide by hanging. A systematic search in five journal databases resulted in 12 case reports. All articles passed the selection criteria and were appraised using JBI critical appraisal worksheet for case reports. Fourteen victims were reported which in most of the cases psychosocial background were reported. Domestic violence was the common background. Reef knot was the majority knot being used. The autopsy findings vary in the studies, some of which reported intact larynx, thyroid


INTRODUCTION
Hanging is the most common method of suicide in the world, with a case fatality rate around 69-84%, slightly lower than the shooting causes [1,2]. Several identified factors have related to suicide by hanging. They are poor education, unemployment, domestic and financial problems [3][4][5][6]. Unlike suicides, homicides by hanging cases are rarely reported and its number is still small. Because of the autopsies were not routinely performed, the number of undetected cases might be higher [7].
Currently, there is no systematic review summarizing the typical characteristics of homicide by hanging. The determination of cause of death in homicidal hanging is difficult and yet challenging because evidence of murder is disguised by hanging the victim to make it look like suicidal hanging. Therefore, a careful autopsy is needed to recognize the signs that might be retrospective pointers towards homicidal hanging [8,9]. Cordner

2.1.Definition of homicide by hanging
Hanging is a form of blunt trauma to the neck. The force exerted on the neck is coming from body weight and gravity force of body parts. In the case of murder, the hanging is done by the perpetrator and the victim has no intention to attempt suicide [11]. Homicide by hanging means the hanging as a method of killing and/or the hanging as a method to disguise the crime evidence.

2.2.Inclusion and exclusion criteria
The selection of studies included in this report was based on inclusion criteria and exclusion criteria. The studies included in the report were: (1)

2.3.Searching and selection strategies
The strategies used in writing this review: (1) Literature searching was carried out in the following journal databases: PubMed, Scopus, EBSCOhost, Cochrane, and Westlaw from 7 to 10 May 2021. The keyword used were "homicidal hanging" and its synonyms.
(2) Manual search based on the reference list or bibliography on selected articles from the journal database mentioned above.
(3) All articles were critically appraised by using The Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Case Report [12]. This critical appraisal was conducted for risk of bias or qualitative quality assessment.

2.4.Data extraction
The data summarized in this review are demographic characteristics of the
Case reports were published in the range of 1988 to the latest report in 2019.

3.3.Psychiatric and social history
Social history was assessed in 10 of 12 cases. Domestic problems are described in 8 cases, 3 cases of which are children of problematic parents [17,22,23]. One report is a business problem between families [24] and one other report is a kidnapping case [19]. The other 2 cases did not describe either the social history of the perpetrator or the victim [16,23].
History of psychiatric disorders was described in 5 of 12 cases [15,17,20,22,23]. In 2 cases, the perpetrator had a history of depression and one of them had attempted suicide [15,22]. In the other 2 cases, the perpetrator had a psychotic disorder and a history of treatment in a psychiatric hospital [17,23]. In one case, the perpetrator had a paranoid personality disorder which led to a divorce from the victim [20].  [14].
The materials used also vary, but the most widely reported is metal wire. This finding can be related to hanging locations, which are mostly outside the house. Therefore, the perpetrator uses objects found at that location [8].

3.5.Neck autopsy findings
On examination, several dry blood spots or abrasions were found around the ligature [13]. Minor abrasions of the neck skin are found on the anterior side of the neck, in the form of a colon (double dot) and a crescent lesion [20], and redness around the scar due to subcutaneous bleeding [24].

3.6.Violence signs
Signs of violence found in hanging murder cases vary, from the presence to the absence of signs of violence [17,22,23].
The finding of a left arm fracture was only reported by Vieira et al [18]. Only two case reports describe sharp violence [14,19]. In the case report by Zummerova et al. sharp wounds were found on both fingers [14].  [14,19].
Only one case report mentioned sexual violence [24]. Bruises were found on the labia majora and labia minora of rape victims with multiple tears on the inferior side. Fresh tears were also found in the annular hymen at 7 o'clock [24]. Other signs of violence were mouth gagging and hand ties [15].

3.8.Victim's death investigation results
The autopsy findings are generally consistent in explaining the victim's death caused by asphyxia due to hanging. Some of the events that preceded the hanging were acts of weakening the victim using alcohol [14,21], violence [14,21], or involving more than one perpetrator [21,24]

CONCLUSIONS
Conclusions of homicidal hanging based solely on external examination and autopsy results are difficult. Nonetheless, we recommend that external examination and autopsy be performed in all cases of unnatural death. Homicidal hanging cases are prone to be considered as suicidal hanging. Therefore, forensic pathologists should consider several other aspects, starting from the demographic characteristics of the victim, location of victim's findings, social and psychiatric history, ligature's characteristic, signs of violence and toxicological analysis result.
All these aspects can lead forensic officers to a comprehensive suspicion of homicidal hanging. Forensic officers are not burdened to prove the manner of death, because that task is the investigator's authority. However, the results of forensic examination will be useful to conduct a thorough investigation, trying to find a possible perpetrator, and other supporting evidence. Homicide by hanging can be excluded when all other possibilities have also been eliminated.