Relationship of sharp force injuries to motivation

Abstract

Forensic pathologists are often expected to provide an opinion on the intention of the assailant in sharp force fatalities. A retrospective study was carried out on reports of post-mortems of victims of sharp force trauma over five years. The position and type of injuries were recorded and related to the known motivation for murder. Victims of different motives of killing had an almost similar injury pattern. There is no significant association of the pathology of sharp force injuries with the motive of killing.

Keywords

Sharp force trauma homicide motive for killing number of injuries medico-legal opinion

Introduction

Sharp force injuries contribute to a significant proportion of violent murders worldwide and are the most predominant method of homicide in Europe.^1,2 In the United States homicides are frequently committed with guns because they are readily available.^3–8 However, the use of sharp force is still not uncommon. Twenty-two per cent of the homicidal deaths in the western province of Sri Lanka are due to sharp force trauma.⁹ Forensic pathologists are often expected to provide an opinion about many important factors in sharp force fatalities in addition to the cause of death. Some of these include the manner of death, type of the weapon, the awareness of the victim, type, number and anatomical distribution of injuries, the shape, size, length, and depth of injuries and the extent of internal injuries are important in the reconstruction of the crime and crucial for the formation of such opinions.

Accurate and objective forensic opinion based on scientific evidence is essential for justice. Miscarriage of justice and wrongful convictions are increasingly reported in the field of forensic medicine due to controversial medical evidence presented at trials. Balanced and reasonable expert opinions from the forensic pathologist can lead to justice for both the prosecution and the defence in a criminal trial.

A revisit to the findings and decisive factors in a homicidal sharp force murder and correlation of these with the historical motive for the killing is crucial to ensure an impartial medico-legal opinion and justice in these cases.

Objective

The aim of the study was to look into the characteristics of homicidal sharp force injuries and their relationship to the known motive of killing and understand how a medico-legal opinion may be influenced by them.

Study design

A retrospective descriptive study was made based on reports of post-mortems performed on the victims of murder by sharp force trauma during the past five years. Historical evidence on the motive of killing was obtained from the records made by the medical officers based on statements by the police and the other informants. The information was gathered on a pro forma basis. The data were analysed using a software package for statistical analysis.

Results

Out of 76 fatalities analysed, 97% (n = 74) were male victims. Eighty-two per cent of the victims (n = 62) were aged under 40 years while 34 of them belonged to the 20–30 year age group (Table 1).

Table 1.

Age distribution of the victims.

Age group (years)	Number of victims
<20	4
20–30	34
30–40	24
40–50	6
>50	8

As stated by the relatives and the investigators, previous enmity was the motive for killing in 56% (n = 42) while 16% (n = 12) of the fatalities were due to drunken brawls. Sudden provocation accounted for 13% (n = 10) while other motives identified were family disputes, 5% (n = 4), and romantic tangles, 5% (n = 4). The motive was not known to the relations or investigators in 5% (n = 4) of the cases.

Sixty-one per cent (n = 46) of incidents occurred at night. The majority, 42% (n = 32), had only stab injuries while both stab injuries and incised injuries were present in 18% (n = 14) of the cases. Twenty-four per cent (n = 18) had blunt force injuries as well as sharp force injuries. Incised injuries alone were found in 16% (n = 12) of the cases.

The fatal injuries were stab wounds in the majority of cases (58%; n = 44). Incised injuries were recognized as the fatal injuries in 32% (n = 24) (Table 2).

Table 2.

Type of fatal injury.

Type of the fatal injury	Number
Stab	44 (58%)
Cut	24 (31%)
Both stab and cut	2 (3%)
Other (blunt)	6 (8%)

Forty-four per cent (n = 34) had 1–3 injuries while there were 40% (n = 30) with more than seven injuries, out of which 24% (n = 18) had more than 10 injuries (Table 3).

Table 3.

Number of injuries present.

Number of injuries	Fatalities
1–3	34 (44%)
4–6	12 (16%)
7–10	12 (16%)
>10	18 (24%)

Sixty-six per cent (n = 50) had a single fatal injury while the rest (34%; n = 26) had multiple fatal injuries. However, only six of them had more than five fatal injuries.

Eight out of the 10 fatalities resulted from sudden provocation and 10 out of the 12 fatalities due to drunken brawls had a single fatal injury. Victims of homicide due to previous enmity and other motives had an equal distribution for single and multiple fatal injuries (Table 4).

Table 4.

Number of fatal injuries in relation to motive of killing.

Number of fatal injuries	Previous enmity	Family dispute	Sudden provocation	Drunken brawl	Romantic tangle	Unknown
1	20	2	8	10	2	4
Multiple	22	2	2	2	2	0

When both stab and incised injuries are considered, the chest was the most common site for fatal injuries (34%; n = 26). Twenty-six per cent (n = 20) had fatal injuries in more than one site (Table 5).

Table 5.

Location of the fatal injury.

Location of the fatal injury	Number of fatalities
Chest	26 (34%)
Neck	10 (13%)
Head	14 (19%)
Abdomen	6 (8%)
Multiple (chest, abdomen and neck)	20 (26%)

When considering stab injuries alone, the chest was the location of most of the fatal injuries 59% (n = 26). Forty-two per cent (n = 10) of the victims of fatal incised injuries were injured in the neck.

Many victims had multiple internal injuries. There were 24 victims with injuries to great vessels, and injuries to the heart and lung were found in 22 victims. Injuries to brain were seen in 18 cases and abdominal organs were affected in 14. Injuries of self-defence were noted in only 55% of cases (n = 42).

Discussion

Injuries caused by sharp force trauma are common worldwide and most fatalities caused by them are homicides. During the period of the Sri Lankan civil war, firearms were the most common method of homicide in the western province, while sharp force trauma was placed fourth, explosives and blunt force trauma were placed second and third, respectively.⁸ When war-related fatalities were excluded sharp force trauma amounted to 22% of the homicides in the western province of Sri Lanka.¹⁰

Studies worldwide have shown that most victims of sharp force murders are among younger age groups.^1,11,12 Similarly, our study revealed that the majority were aged less than 40. The study also revealed that 97% of the victims were males. Male predominance was observed with sharp force violence in other forms of murder.^13,14

The motive for killing in most cases was previous enmity. In a study on homicides in the western province of Sri Lanka, previous enmity was identified as the main motive for killing, when the war-related fatalities were excluded.⁹ This study confirmed the results of the previous study. Similarly revenge was the main motive for homicides in Bastar Region of Chhattisgarh.¹⁵

The majority (61%) of the incidents had occurred during the night and this is commonly observed in murders since darkness provides the opportunity to commit crimes without witnesses.^15,16

The fatal injuries in 58% of cases were stab injuries. This is in keeping with the findings of other studies where Farhat Hussain Mirza et al. had reported 69% of sharp weapon deaths were due to stab wounds.¹²

Different studies have reported different results for the presence of single fatal wounds in murders. According to a study by Bajanawsky et al. isolated stab injuries were found in 22% of the cases while it was 67% in a study by Blomquist et al.^17,18 These further highlight the difficulty in interpreting the manner of death based on the number of stab wounds.¹⁹

Single fatal injury was commonly observed in association with sudden provocation and drunken brawls. However, the numbers of cases due to these motives were insufficient to come to a conclusion. Victims of previous enmity and other motives had both single and multiple fatal injuries equally distributed. Thus, there is no direct correlation of the motive with the number of fatal wounds.

The chest was the target site for injury in 34% of sharp force trauma incidents while the percentage increased to 59% when stab injuries alone were considered. Bajanawsky et al. reported presence of fatal stab wounds to the anterior left chest in 50% of the cases.¹⁷ Ten out of 24 fatal incised injuries (42%) were located on the neck. The neck is a common site for homicidal incised injuries.¹² The neck is also the most common site of suicidal incised injuries.²⁰

Multiple internal organs were found to be affected in two victims and the majority had injuries to the great vessels while heart and lungs had been affected equally. In a study of sharp injury fatalities in New York, 71% had injuries to the heart and/or the great vessels.²¹ However, in a study done in Karachi-Pakistan, intestines were commonly affected with sharp force trauma.¹² Fifty-five per cent of the victims had injuries of self-defence. Defence injuries were reported in 49% of the sharp force injury homicides in New York.²¹ The incidence of defence injuries ranged between 37.1 and 49.5% in several autopsy studies.²²

Conclusions

Young males are commonly the victims of homicidal sharp force trauma. Stab injuries are the most frequently observed wounds. The presence of multiple injuries and involvement of vital organs are closely associated with homicidal sharp force trauma. There is no significant association of the pathology of sharp force injuries with the motive of killing. A comparative study of non-lethal sharp force trauma and that of suicidal sharp force trauma could be useful.

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