Post Mortem Changes

DEATH INVESTIGATION The Coroner System dates back to feudal England. It is the most common system within the United States as far as dealing with determination of death, and any legal/forensic ramifications associated with death.

Cause of Death (CoD) One of the major determinations made in forensic pathology is the Cause of Death (CoD). CoD is defined as the injury or disease producing a physiologic derangement in the body that results in the individuals’ death. The immediate CoD is different than the proximate CoD. As an example – if someone is shot on Monday, and dies from a shooting-related infection 2 weeks later, the shooting would be listed as the proximate CoD, and the infection as the immediate CoD.

Mechanism of Death Correlated with the Cod is the Mechanism of Death. The Mechanism of Death is the physiologic derangement/s produced by the CoD, thus resulting in death.

Manner of Death (MoD) The Manner of Death (MoD) is, perhaps, the most important determination made – at least from a legal point of view. The MoD explains how the cause of death came about. Mod falls into one of the following five categories: natural accident suicide homicide undetermined

Autopsy Either Medical or Forensic Medical autopsies are done to determine the medical reason a person died, i.e., congestive heart failure, myocardial infarction, non-specific cardiomyopathy, etc. From the point of view of a death certificate – all of these would be classified as "natural causes" in terms of MoD. The following are some typical situations in which an autopsy would likely be performed:

When do they Autopsy Each specific case has characteristics that will determine whether an autopsy is actually done, however. violent deaths/accidents suicides homicides. Suspicious deaths unexpected deaths unattended deaths deaths in custody (always done)

The Autopsy External Exam (clothing, exterier of the body) Internal Exam (The surgical portion) Samples are taken Major organs are sampled, with emphasis given to brain, liver, kidneys, and adipose. blood, urine, CSF, and intra-ocular fluids (aqueous & vitreous) (based on TOD)

Y Incision

What happens to the samples? Toxicology Tox screens are done as "panels" (e.g., an opioid panel, or an amphetamine panel, or cannabis, or......) - and only the specific drugs that are in that particular panel can be tested for. There are many toxins/poisons that simply aren’t on any standard tox panel and, therefore, would not show up on a standard tox screening. Also - poisoning can be done with ELEVATED levels of naturally occurring chemicals!

Poisoning

Determination of Time of Death (ToD) Time of death (ToD) is most often used when talking about a death that has occurred within a relatively recent time frame – the last day or two. As the window of time increases, a better term is Post Mortem Interval, or PMI.

Algor Mortis Post-mortem cooling. Once a person dies, cellular metabolism ceases and, therefore, the production of heat. i.e., it is not as accurate as the writers of television forensic shows might have you believe. And, once the body has reach ambient temperature, it is of no significant value. (98.4° - rectal temp) / 1.5 = hours since death This is a rough calculation effected by many variables

Heat Loss Mechanisms conduction - transfer of heat by direct contact with another object radiation - transfer of heat to surrounding air & objects by infrared waves convection - transfer of heat through moving air currents adjacent to the body evaporation – loss of heat due to the conversion of water from the liquid phase to the gaseous phase.

Factors that influence heat loss. Temperature gradient Air movement(convection) Clothing Body fat Surface area environment

Livor Mortis The settling of blood in dependent tissues of the body. Usually starting within the first 3-5 hours following death, and reaching completion by 8 – 12 hours This discoloration does not occur in the areas of the body that are in contact with the ground or another object, as the capillaries are compressed. As the vessel wall become permeable due to decomposition,blood leaks through them and stains the tissue. This is the reason for fixation of hypostasis If the body is moved prior to fixation of the blood, livor mortis can "shift" to a new region of the body. Movement of the body after fixation will not cause a shift in the livor mortis pattern, and is a good indicator that the body has been moved.

Rigor Mortis Rigor mortis (or simply rigor) is commonly known as death rigor, or the rigidity of death.

Rigor Mortis Timeline

Things that accelerate Rigor Mortis prior exercise seizures electrocution hyperpyrexia hot environment (and the resulting hyperthermia) acidosis uremia

Rigor mortis can be delayed by the following: cold environment hypothermia decreased muscle mass carbon monoxide (CO) exposure Therefore, anything that makes the tissue warmer or more acidic will tend to shorten the time line for onset, where as cooling or preventing elevated H+ will lengthen it.

Decomposition & Putrefaction Decomposition simply refers to the breakdown of something – in this case, of the tissues of the human body.

Appearance of the eyes If the eyes remain open at time of death they will become cloudy within 2-3 hours. If the eyes are closed after death, then the change will take longer (approximately 24 hours)

Stomach contents Undigested stomach contents Death occurred 1-2 hours after meal Stomach empty Death occurred 4-6 hours after the meal Small intestines empty Death occurred 12+ hours after meal.

Gun Shot Wounds

Entry wounds

Exit Wounds

Strangulation

Knife Wounds

Drowning victims

Electrocution

Bite marks