While many training or new crime investigators may wonder why they may be required to attend the autopsy of a crime victim, it is an essential extension of the crime scene and offers a wealth of information that helps to put physical evidence in perspective. Even if a crime scene investigator is not required by department policy to attend such autopsies, it is recommended, time allowing, in order to offer additional information or interpretation of the cause or manner of death of a victim. An autopsy is required in all homicide cases. As such, crime scene investigators need to be familiar with autopsy protocol, procedures and terminology.

The medical examiner may also be known as the coroner or a pathologist, depending on area jurisdiction and population. No matter by which title they are referred, he or she must be a qualified doctor of medicine and a certified pathologist.  A medical examiner is a key component to any homicide investigation, and they must investigate and certify any death that has occurred due to circumstances such as: 

• Obvious homicide
• Violent death
• Suicide
• Accident
• Unexplained death

The autopsy is designed to determine the cause of death, the mechanism of death, and the manner of death. In some cases, the cause of death cannot be determined, due to various reasons, including decomposition.

            Cause of Death -- is usually defined as the injury or disease that caused the death of an individual. Stab wounds, gunshot wounds or blunt force trauma are all causes of violent death. 

            Mechanism of Death -- is defined as what directly caused the death to occur. An example is hemorrhage. A gunshot wound might not be fatal in and of itself, but if the victim bleeds to death, loss of blood becomes the mechanism of death. 

            Manner of Death -- is defined as "How the death occurred". Such examples are homicide, accidental, suicide and natural. In addition, when necessary, a medical examiner may write "Undetermined" under this section of the autopsy report.

The moment death occurs, decomposition will set in. Without going into the various stages that make up this process, a crime scene investigator should know that the decomposition process may alter a victim's body to the point where determining cause of death may be impossible. Insects or animals that have gained access to the victim may make identification difficult, as will the result of a body having been left in water for long periods of time. In some cases, decomposition and putrefaction may cause distortions or bruises on the skin of the victim that may look like assault wounds, but are the natural by-product of the decomposition process. This is one reason why it is important for a medical examiner or pathologist to examine the victim as soon as possible.

On the other end of the spectrum, a victim of homicide may not have any outward signs of physical trauma at all. Such is the case with internal injuries or some poisonings, and suffocation.

In many cases changes in the body progress at different speeds, due to temperature and location of the body. As such, estimating time of death can prove tricky in many cases, and the expertise of a medical examiner will be needed. Until that determination can be made, a crime scene investigator should realize some of the basic changes that occur in a body following death.

Changes in the eyes become noticeable within a few minutes to a few hours after death. The cornea is shrouded with a film and becomes dull in appearance. The presentation of such an appearance will depend on temperature, humidity and whether or not the victim's eyes are open or closed.

The body also starts to cool immediately after death, and such cooling also depends on a multiplicity of factors, including ambient temperature of the crime scene location, and clothing. The core body temperature is recorded most accurately via a thermometer inserted into the liver, and the comparison of that temperature to the ambient temperature is used to determine an approximate time of death.

Rigidity is also a factor in determining time of death. Chemical changes in the body usually produce stiffening in the body between 2 to 6 hours of death. The stiffening starts in the smallest muscle of the body first, such as the jaw and fingers, and progresses to the larger muscles and muscle groups. This process is called rigor mortis and is usually completed in within 6 to 12 hours. Then, the process reverses itself, which may take up to several days.

Decomposition and putrefaction are noticeable within 24 hours of the death of a victim. Tissues soften and liquefy and gases within the body start to cause the breakdown and disintegration of body tissues. Some environments may hasten decomposition and putrefaction, and again, it is best left to the medical examiner to determine time and cause of death in such cases.

At any rate, the information gathered from an autopsy can help the investigation by offering a wide range of facts, including: 

• Type of weapon used in the death
• Determination of fatal wound
• Whether the victim was under the influence of any drugs or alcohol
• Estimated time of death
• Evidence of struggle
• Evidence of sexual assault
• Whether various injuries were ante- or post-mortem

The medical examiner will thoroughly examine the body of the victim and note the size, location, character and type or types of wounds suffered by the victim. In addition, the medical examiner may be able to tell the order in which various wounds occurred, and to a certain degree, the time such wounds were inflicted.

Most autopsies of victims of violent death will also be able to pinpoint the weapon used in the commission of the assault. The crime scene investigator and the lead detective assigned to the case can work together with the medical examiner to involve the following procedure revolving around the examination of the victim of a violent crime: 

• Examination the crime scene
• Identify the victim
• Examine the body at the medical examiner's office
• Perform toxicological tests on body fluids and tissues 

Together, the crime scene investigator and the medical examiner will carefully examine, collect and preserve any evidence found on the victim's clothing or person. Only then are clothes carefully removed and placed in separate evidence bags or containers. In most cases of a violent attack, the hands of the victim are covered with paper bags at the scene of the crime in order to preserve any fibers, skin or hairs that may have been trapped under a victim's fingernails or in their hands during an attack.

Clothes are not torn or cut off the victim at the medical examiner's office, but carefully removed to preserve them. Any missing buttons, snaps, or other damage to clothing is photographed and recorded by notes taken by the crime scene investigator, homicide detective, and medical examiner, or all three.

Following that procedure, the body of the victim is measured, weighed and physical description noted. The body is then examined again for any signs of evidence before it is gently washed, removing blood and other debris. Injuries are then recorded, measured and examined. Photographs are taken, which a ruler or other scale marker in photographs to determine scale. X-rays are then taken and fluoroscope examination performed to note the presence of bullets or metals.

The hands and wrists of violent crime victims are carefully examined for the presence of defense wounds and when necessary, fingernails of the victim are clipped and saved for analysis. In many cases, victims defending themselves may have DNA of their attacker's skin or blood cells under the nails. In the case of a sexual assault, pubic hairs and scalp hairs are taken as samples for comparison to later suspect samples.

When it comes to the internal examination of the victim, the medical examiner will make examinations of the victim's head, scalp and brain, as well as the neck, chest, abdomen and lower areas of the victim. Bullets or other foreign objects are removed and sealed in containers, tubes or bags for further analysis.

A traditional "Y" incision will be made on the victim's chest and abdomen, the skin pulled back and the internal organs examined. In general, a certain protocol is followed, which will allow the medical examiner to cover all aspects of the victim's external and internal organs. Such a protocol will contain the following information:

• External examination
• Evidence of external and internal injuries
• Examination of the head and brain
• Internal examination of major body organs
• Anatomical findings
• Toxicological findings
• Medical Examiner's Opinion