Suicide Investigation (World of Forensic Science)
When the medical examiner (ME) is faced with an unexplained death, he or she has to determine whether the manner of death is natural, accidental, homicidal, or suicidal. The first involves disease, the other three manners involve some form of physical trauma. In a suicide, trauma is inflicted by the victim on himself. Gunshot wounds, jumping from a great height, hanging, and drug overdose are common causes of suicide. However, such deaths can also be caused by homicide or accident. In the case of a shooting, it can sometimes be obvious from the autopsy whether or not the death was likely to be a suicide. With a drug overdose, however, the autopsy findings are the same whatever the victim's intent, and the investigator must look carefully at the circumstances to arrive at the correct verdict. If the investigator comes to the wrong conclusion, a killer may either escape or be unjustly convicted. Suicide is always traumatic for those left behind. If an accident or homicide is wrongly ruled as a suicide, then the family of the deceased is caused unnecessary grief. In other words, suicide investigations must be undertaken with great care, because some cases are complicated.
Poisoning remains the most common method of suicide, especially among women. It is perceived as being less traumatic than other methods and with the widespread availability of alcohol and drugs, the means are easy to obtain. However, poisoning is also often accidental, especially if the victim is confused, which may happen if they have been drinking or ill, for example. Under these circumstances the victim may mistakenly take too many sleeping pills or painkillers. Poisoning could also be a homicidal act. Although murder by poisoning today is somewhat less common than in previous centuries, the pathologist should never rule out the possibility.
The suicidal use of corrosive agents such as acid or weed killer has decreased dramatically in recent years, perhaps because such chemicals are now less readily available than they used to be. Cyanide is a deadly poison that often features in books or films about murder and suicide. However, cyanide poisoning is not very common these days, especially as a tool of homicide. Cyanide turns to lethal hydrogen cyanide gas on contact with the acid of the stomach. Hydrogen cyanide prevents the body's cells from using oxygen; this gives the blood a characteristic pink color that will be evident to the pathologist on autopsy. The victim's face is often a brick-red hue after cyanide poisoning.
Aspirin and barbiturates are also less likely to be used as suicidal agents than previously. Doctors rarely prescribe barbiturates these days, but various other prescription and over-the-counter drugs can be equally lethal. There has been an increase in self-poisoning with antidepressants and acetaminophen. Moves to restrict the amount of some over-the-counter drugs purchased at one time have deterred some impulsive suicides. However, the person who is bent on suicide will merely collect up enough pills to commit the act.
It is not uncommon for a "cocktail" of drugs to be taken in suicide. The pathologist must take samples from blood, urine, and various body tissues and then has the difficult task of trying to work out what contribution each component of the cocktail made to the death. The presence of a suicide note at the scene of a poisoning (or other suicide) may be taken as an indication of suicide rather than an accident. However, the absence of a note does not mean the act was necessarily accidental. Some people simply do not leave a note, perhaps to protect the feelings of loved ones by trying to make the act look accidental. Moreover, forged notes may be used to help stage a homicide as a suicide. As ever, all the evidence must be carefully assessed to arrive at the truth.
Carbon monoxide poisoning accounts for many suicides, the classic method being to sit in a car with the engine running in a closed garage. Under such circumstances, it may take only a few minutes for a lethal level of carbon monoxide to build up in
Hangings are nearly always suicidal in adults and teenagers, though usually accidental among children. Commonly the mechanism of death in hanging is asphyxiation from compression of the carotid arteries and the airways due to the pressure of the ligature. However, if the body drops through a height on hanging, death may be from cardiac arrest from pressure on the vagus nerve in the neck. The medical examiner must distinguish between hanging and asphyxiation caused by other means such as manual strangulation and smothering. Neck marks are common, but may not be present if a soft material like a scarf or a sheet has been used. The marks run diagonally across the neck in a hanging, but are horizontal after manual strangulation. Toxicology testing for drugs or alcohol plays an important role in the investigation of a hanging. A suicidal victim may take drugs to get up courage to perform the act; a murder victim may be subdued or made unconscious in the case of a homicide. Homicidal hanging of a fully conscious able-bodied person is virtually impossible. Suicidal strangulation by a ligature is rare, but not impossible, and must be considered when a victim has been strangled. It takes 15 seconds or so to lose consciousness in strangulation, which allows the victim time to loop or knot a ligature around their neck. Another form of suicidal asphyxiation is smothering, where the victim places a plastic bag over the head, securing it in place with tape or a rope. In such cases, the face is often pale and does not exhibit the congestion or protruding tongue seen in strangulation.
When a body is found in water, the pathologist must consider the possibility of suicide, although most drownings, if this is the cause of death, are accidental. If the person is weighted down, perhaps by clutching stones or rocks or having them in their pockets, then this may indicate suicide.
Deciding whether a shooting was suicide, homicide, or an accident can be a major issue for the medical examiner. In the case of a suicide, the gunshot wound, or wounds, must be found in a site on the body consistent with the range of the deceased's arm. These wound sites often depend on the type of weapon that is used. Long-barreled weapons such as rifles and short-barreled weapons, like handguns, can both be used to inflict injuries inside the mouth, under the chin, on the front of the neck, and the center of the forehead, all of which will readily inflict a fatal wound to the brain. The classic discharge to the temple is found only with a handgun and the wound will be on the same side of the head as the dominant hand of the victim. A left-handed person cannot readily shoot himself in the right temple.
People rarely shoot themselves in the eye or abdomen. It is also virtually impossible to shoot yourself in the back. Women rarely shoot themselves, either intentionally or by accident. Multiple gunshot wounds are nearly always the result of homicide, although they are not unknown in suicide.
In a suicidal shooting, the weapon must be found at the scene. It may, however, be at some distance from the body because the recoil of the weapon on shooting can fling it away from the victim. If no weapon is found, homicide is the most likely verdict unless someone has been interfering with the scene of the crime and removed the gun. However, investigators must always be alert to the possibility of the staging of a homicide to look like a suicide by placing the gun by the side of the body. In short, deciding the manner of death in a shooting can be difficult, and it is important to consider all the evidence relating to the investigation.
Some railways deaths are suicides. People may lie on the track with their neck across a rail, which results in decapitation. Jumping in front of a moving train is a relatively common form of suicide. The injuries caused depend upon the exact events and are usually extensive. However, some victims do survive jumping in front of a train. It is important to distinguish between homicide and suicide in railway injuries, because it is not unknown for people to be pushed in front of moving trains. Similarly, a homicide may be staged as a suicide by placing a body on a railway track. In such cases, the pathologist may see evidence of injuries that may have been inflicted before the impact of the train on the body.
These are some of the most common methods of suicide, but suicide needs to be considered as a possible manner of death in many cases referred to the medical examiner. Often it is not possible to distinguish between accident and suicide on the evidence given, in which case an open verdict may reasonably be given.
SEE ALSO Death, cause of; Death, mechanism of.