'defence wounds'

The presence of 'defensive wounds' implies that the victim was able to put up some resistance to an assault, at some stage during that assault. 

The victim is injured whilst raising his/her hands and arms up to protect vital organs/ body parts, such as the head and face, whilst legs are raised when the victim is on the ground to protect the abdomen etc.

Injuries seen include bruises, abrasions, fractures (particularly metacarpal fractures) and incised wounds, depending upon which part of the assailant or weapon impacted against the victim’s arms etc.

Mechanism of injury to hands/ arms defending an overarm knife attack

Source: Richard Jones (WIFM)

Mechanism of ulnar border of forearm 'defence injury' in a knife attack

Source: Richard Jones (WIFM)

Mechanism of palm of hand 'defence injury' in a knife attack

Source: Richard Jones (WIFM)

Defence wounds obtained whilst fending off an assailant with a knife are typically found on the dorsum of the hand and backs of the forearms (ulnar border) and upper arms.

Where an attempt has been made to grab the knife blade from the assailant, incised wounds may be found between the thumb and fingers, across the palms or in the webspace between the bases of the thumb/ index finger.

The likelihood of there being defensive injuries increases with an increasing number of knife wounds, and their presence or absence should be specifically looked for and documented in the medical notes.

Hunt and Cowling (1991) found that defence wounds were found in only 15% of those who exhibited a single stab wound, but were seen in 54% of those with multiple stab wounds.

Karlsson (1998) identified defensive injuries in 41% of homicide victims, but not at all in suicides.

Characteristics of ‘defence wounds’

• Raising hands to protect chest/ head/ neck – wounds on dorsum of hand, back of forearms and upper arms
• Grabbing weapon with thumb with hand in opposition – palms and ventral surfaces of fingers
• Defence wound frequency increases with number of stab wounds

Sharp force defence wounds (source: Nikolas Medien Hande)

self-inflicted sharp force wounds

These wounds may have arisen in attempt to harm oneself, or to bolster a claim that one was in fact assaulted.

Where the injured part is the neck, there are several features that assist in the determination of whether the wound was self-inflicted or not.

Suicidal cut-throat is less common than at the turn of the 19th Century (when it represented 61% of a series of suicides reported in Prussia in 1900) and that variation in the use of different sharp objects over time probably represents a combination of availability of different objects and culture (the disappearance of the use of hat-pins etc as a means of suicide is an illustration of this) (Karlsson 1998).

A 'cut-throat' injury (said to have been self-inflicted)

Source: Eduard Ritter von Hofmann, 1898 via Visible Proofs exhibition, National Library of Medicine

Where self-harm is the aim, the wound produced may be extremely deep, separating the neck structures as far down as the pre-vertebral fascia.

However, such deep injuries may also be the result of homicidal intent during an assault, so the depth of injury cannot necessarily be used to infer intent.

The wound may be accompanied by several linear superficial injures – tentative or hesitation marks, (Vanezis and West 1983) which probably represent the individual testing their ‘resolve’ before the final act, or slowly building up their mental response to the pain of the wound infliction. Karger et al (2000) found tentative marks in 77% of sharp force suicides (ranging from 1 to 60 per case).

If the heart is the target, however, there may be no such hesitation marks – just a single plunge of the knife into the chest cavity. In such cases, the absence of any involvement of clothing may support the inference that the wound was self-inflicted, but Karger et al (2000) analysed records of 65 consecutive cases of suicide by sharp force, and found that perforation of clothing was present in 52% of stab injuries to the trunk.

Suicidal 'cutthroats' are seen in men more than women, compared to self-inflicted wounds of the wrist, which are seen more in women than men, and are also said to be more prevalent in drug abusers.

Self-inflicted wounds of the wrist also tend to be found on the non-dominant wrist (for obvious logistical reasons), and are usually accompanied by tentative or hesitation marks that are fine linear incisions grouped in the area of the final deeper incision. Veins and soft tissues are injured, but most self-inflicted wounds of the wrist fail to do more severe damage, due to an ignorance of the underlying anatomy.

Wrist wounds tend to be found on the flexor or volar aspect compared to defensive incised wounds inflicted whilst defending oneself against an assault, where they tend to be found more on the extensor aspects of the forearms.

Karlsson (1998) concludes from studies in Sweden that single wound suicides generally have deep stab wounds to the chest (orientated horizontally as opposed to vertically orientated chest wounds that are more consistent with assault), whereas those found with multiple wounds involve the extremities.

Self-inflicted scratches from a knife

Source: Wikipedia

Features of self-inflicted wounds

• Usually involve accessible body parts – particularly the neck, wrists and chest wall and follow the contours of the body
• Injured parts are ‘less sensitive’ i.e. rarely involve lips, ears etc
• Clothes are often (but not always) removed prior to infliction (or pulled aside)
• Tentative or hesitation marks are highly characteristic of self-inflicted wounds
• Seen in women >men
• Usually several superficial wounds with or without a final deeper wound (if self harm is the object)
• Self mutilation e.g. self castration usually indicates severe mental illness

'Suicide through Stabbing' (1898) Eduard Ritter von Hofmann, M.D., Atlas of Legal Medicine, Philadelphia, chromolithograph; Artist A. Schmitson

National Library of Medicine

assault/ homicide

Most homicidal stab wounds are single wounds, and the areas of the body most commonly targeted are the chest, heart and neck.

Where the throat is targeted during an assault, the wounds produced tend to be deeper, and more haphazardly placed. They are produced following a sweeping movement of the knife, and are not associated with tentative or hesitation marks. There are sometimes termination scratch-like abrasions where the knifepoint has been drawn over the skin surface on withdrawal.

The targets of injury are unprotected areas of the body, and the chest is an obvious target due to its closeness to the attacker, and the knowledge that it contains many vital organs. 

The majority of people are right handed, and the majority of assaults are frontal. Wounds received during an assault tend to be clustered on the left side of the body, particularly the chest.

Karlsson (1998) identified homicidal stab wounds being clustered around the head, upper extremities and chest, but found that wounds in the crook of the arm and the lower extremity, as well as the abdomen were more likely to be found in cases of homicide than suicide. He also found that clothing was more likely to be damaged in homicide victims (79%) as opposed to suicides (5%).

Where a knife slash impacts the body it may ‘skip’ along the surface as it passes over natural contours or bony ridges, and result in a discontinuous line of injury. If one looks at the pattern as a whole, the nature of the single slash wound can be appreciated. 

For example, a wound above the eyebrow and on the cheek and the chin may represent one single swipe of the knife, even though there are seemingly 3 injuries. This type of pattern of injury can also be appreciated in defensive wounds of the back of the hand, particularly in those victims with lax skin, such as the elderly.

Wounds that are inflicted during torture tend to be deliberately delivered to cause pain and humiliation rather than incapacitation, and are often found on the face (Purdue 2000). 

They may be associated with more damaging injuries, such as blunt force trauma to the head, or gunshot wounds where the final act is meant to be a fatal one.

Homicidal or aggressive cutthroat injuries can usually be differentiated from suicidal ones by considering the wounds and associated features in context.

Most homicidal cutthroat injuries are inflicted from behind the victim, and the head is pulled back to expose the throat.

A right-handed assailant will inflict a wound from left to right, starting off high (as may be seen in self-inflicted wounds), and running more horizontally to the point of termination. However, there will be no hesitation marks, and wound is often ragged due to relative movement of assailant and victim.

There may also be signs of defensive injuries e.g. to the hands and arms, or bruising on the chest wall or shoulders from being forcibly restrained or pinned against a wall or floor etc (DiMaio and DiMaio 1993).

Where the assailant targets the throat from in front of the victim, the (often horizontally oriented) wounds are caused by slashing movements. Where the wounds are found on the chest, they can be seen as a pattern of horizontal, vertical or circular injuries.

Green (1978) indicated in his research into stab wounds that although it could be argued that a single wound was accidental, the action of removing a knife from a body required considerable effort, and therefore a victim with more than 1 wound could be argued to represent a situation where the assailant was more intent on doing serious harm, thus helping to negate a defence of accident.

Deaths due to sharp force violence by anatomical region - homicides and suicides in Sweden (1983-1993)

Source: Adapted from Karlsson 1998

Summary of main features of sharp force injuries inflicted during an assault

•  Targets are often neck, face and chest, abdomen (and upper extremity)
• Usually single and deep
• Not associated with hesitation/ tentative marks
• Clothing often damaged (e.g. in wounds of the chest)
• May be associated with defensive injuries, or signs of restraint
• Sweeping/ slash in nature
• Homicidal cut-throat from behind may resemble suicidal attempt, but without hesitation marks
• May be accompanied by a clearly homicidal injury, such as a gunshot wound to the head etc

accidental sharp force injury

Accidental incised wounds are commonly the result of either a fall onto broken glass, or through a glazed surface, or during DIY or working with sharp tools.

Where broken glass has caused the injuries, shards or particles of glass may be found contaminating the wound, or protruding from the wound, thus assisting interpretation. 

The wounds may be on the forearms or wrists (due to the hands being outstretched in an attempt to ‘break the fall’), or in the neck region (where the head and neck have passed through the glass, and the neck been damaged by the broken shards).

Tool work on one’s lap, or where the work piece is held into the body for stability may result in wounds to the groin/ femoral region, if the tool or work piece slips and allows the tool to be directed towards the groin.

Other incised or penetrating wounds may occur as the result of vehicular accidents, where wooden stakes are driven into the vehicle and contact the occupant, or where the occupant is ejected from the vehicle and impacts fencing poles etc. Persons falling from a height may also suffer penetrating injuries if their fall is terminated by fencing or railing spikes etc.

therapeutic or diagnostic incised wounds

There are several wounds that can be confused for those inflicted during an assault, for example, chest drain wounds, that have all the characteristics of a stab wound.

Venous cut-down in accident and emergency seems not to be performed as frequently in the UK at this time, but again, the incised wounds caused during this procedure to gain IV access may be confused with incised wounds inflicted by some other modality.

Tracheostomy incisions may masquerade as incised wounds of the neck/ throat.

references

• DiMaio D.J., DiMaio V.J. (1993), ‘Forensic Pathology’, CRC Press
• Green M.A. (1978), ‘Stab wound dynamics – a recording technique for use in medico-legal investigations’, Journal of Forensic Science Society, Vol 18: 161-163
• Hunt A.C., Cowling R.J. (1991), ‘Murder by stabbing’, Forensic Science International, Vol 52:107-112
• Karger B, Niemeyer J, Brinkmann B (2000), 'Suicides by sharp force: typical and atypical features', Int J Legal Med 113:259-262
• Karlsson T (1998), ‘Homicidal and suicidal sharp force fatalities in Stockholm, Sweden. Orientation of entrance wounds in stabs gives information in the classification’, Forensic Science International 93(1) 21-32
• Purdue B.N. (2000), ‘Cutting and piercing wounds’, Chapter 9 in Mason J.K. and Purdue B.N. (Ed), ‘The pathology of trauma’, 3rd Ed, Arnold
• Vanezis P, West IE (1983), 'Tentative injuries in self stabbing', Forensic Science International 21:65-70