Week 7 Lecture
Death investigations, in their most simple form, determine the manner and cause of death through evidence found both at the crime scene and most importantly, from the victim’s body itself. It is important that an investigator views all circumstances of the case in addition to the evidence in making this important determination. If a natural cause, an accident, and a suicide do not appear to fit a particular case, then an investigator must conclude that the victim is dead as a result of the willful killing by another person. Investigators are faced with the task of answering three important questions in homicide investigations. Who is the decedent? What was the cause of death? Who committed the murder?
Issues in the Investigation of Death
All deaths can be classified in one of four ways (the manner of death):
- Deaths can be the result of natural causes (this is most common).
- Deaths can be the result of an accident.
- Deaths can be the result of a suicide.
- Deaths can be the result of a homicide.
In determining the manner of death, investigators must consider the nature of the injuries sustained by the decedent (the cause of death), the characteristics of the decedent, and the circumstances of the death.
Some determinations are based heavily or solely on medical findings.
Sometimes establishing the manner of death is not clear or can only be differentiated by the state of mind of the decedent (impossible to truly know).
Suicides can be best ruled out first through certain indicators:
- The presence of a weapon may indicate suicide.
- Wounds that could have been self-inflicted are another indicator of suicide.
- Lack of defensive wounds is a good indicator of suicide.
- A suicidal motive accompanied with other issues is often indicative of suicide.
- A suicide note may or may not be present.
Patterns and Characteristics of Homicide
- It is a relatively infrequent crime.
- Statistically speaking, most victims and perpetrators share the same characteristics: same age (20-24), sex (male), and race (Blacks kill Blacks, whites kill whites).
- Most often homicides occur as a result of an argument or the commission of another felony (felony murders).
- Most victims and perpetrators know each other prior to the incident.
- Firearms are the most commonly used weapon, followed by knives, then bodily force.
- Homicide has the highest clearance rate of any index offense.
Investigative Considerations with Death and Homicide
Death investigations usually begin with where the body was found (which is often the crime scene as well).
There are three basic questions that need to be answered in death investigations:
Who is the decedent?
- Witnesses, friends, and relatives may be present to inform investigators of this. This question can also be answered through a person’s possessions, scientific methods like DNA and fingerprints, or anthropological facial reconstruction.
What was the cause of death?
- Gun shot wounds are a result of firearms. Shell casings, the presence of entrance and exits wounds, the distance of the gun from the body (contact, close, distant), the amount of trauma sustained, the location of the trauma, and gunshot residue are all important features of firearm deaths that need to be evaluated.
- Cutting wounds involve the slicing of tissue with smooth edges. Stab and puncture wounds will present holes in the tissue. Trauma of this sort often involves excessive bleeding and extreme damage to internal organs.
- Blunt force trauma is characterized by irregular or rough-edged lacerations, bruising, and possibly broken bones in the contact area. Hammers, pipes, crowbars, and clubs often cause it. It is evidenced by hemorrhaging of the upper eyelids.
- Asphyxia is when a person is unable to breathe due to an action or material. It can occur in the form of manual strangulation (with hands), ligature strangulation (such as a rope or purse), hanging, suffocation (smothering), or drowning. Such a death is evidenced by petechial hemorrhaging.
- Poisoning most often occurs accidentally or as a result of a suicide. Indicators of poison consumption depend on the poison ingested (carbon monoxide will turn skin cherry-red whereas certain chemicals will make vomit different colors).
- Drug-overdose deaths are often about determining who supplied the drugs to the victim, because that is a serious crime in and of itself.
- Drugs can be introduced to the body in many ways: intravenous, intramuscular, oral, cutaneous, rectal/vaginal, inhalation, subcutaneous, and sublingual.
Who committed the murder?
Circumstances of the incident and characteristics of the victim are critical in identifying the perpetrators.
Establishing a motive is often useful in reducing the amount of suspects to be considered.
- A motive can be discovered when analyzing diaries, letters, e-mails, telephone records, appointment books, friends, and relatives.
- Physical evidence on the victim’s body or at the crime scene may lead to the killer’s identification.
- Investigators should consider everything as evidence and expect to find physical evidence at homicide crime scenes. It is at homicide scenes where physical evidence is most critical.
- Estimating the time of death is essential to the identification of a suspect for it can be compared to a suspect’s alibi.
Estimating time of death can be done through witnesses or through conditions of the body. The postmortem interval (PMI) guesses time of death through the changes a body goes through after death.
- Algor mortis refers to the cooling process a body goes through after it is dead.
- Livor mortis refers to the blood settling of the body after death that discolors the skin.
- Rigor mortis is the rigidity of the muscles of a body after death.
- Potassium levels in the vitreous humor can be indicative of the time of death.
- If a victim’s last meal is known, the contents of the victim’s stomach or gastrointestinal tract can be useful in estimating time of death.
- The degree of decomposition can also determine time of death.
- Depending upon the environment, insect and animal activity are also relevant. An insect’s presence, stage of development, and contents of their gut provide a temporal dimension to the death of an individual.
The Value of an Autopsy in Establishing the Cause and Manner of Death
- The external examination consists of photographing the body, the belongings, the clothing, and other parts of the body of relevance.
- The internal examination consists of opening the chest, abdominal, pelvic cavity, and the skull to inspect internal organs and injuries related to the cause of death.