Final - Death Investigations/Post Mortem Interval

Estimating Time of Death

A pathologist can *never* give an exact time of death, but there are characteristics that the examiner can analyze in order to arrive at an *approximate of death*

Insect evidence should be collected:

At the scene by a forensic entomologist or trained investigator

Cycle of Blow Flys

Blow Flies come within half hour because they can smell from up to a mile away They hatch into larvae/maggots After 14 days adult blowflies emerge and find a new body

Primary Insect used in Forensic Entomology

Blow Fly

Hanging cases will typically display:

Blue appearance in the face

What part of a decedents body resists rapid decomposition and is used by forensic anthropologists to provide information about descendent?

Bones

A body that displays a cherry-red discoloration might lead a pathologist to suspect which kind of poisoning:

Carbon monoxide

Death at a fire scene is most often attributed to:

Carbon monoxide

Asphyxia →

Caused by an interference with oxygen, such as carbon monoxide or hanging *Petechial Hemorrhages* in victims eyes comes from hanging

Blunt Force Injuries →

Caused by non-sharpened objects, such as a hammer

Sharp Force Injuries →

Caused by weapons with sharp edges, such as knives or blades

Forensic Anthropology

Concerned primarily with the identification and examination of human skeletal remains Examination of bones may reveal their sex, height, age, race, and skeletal injury EX: Pelvic bones help determine gender EX: Male skulls are larger and have more pronounced brow bone

Putrefaction and autolysis are two types of ____ processes:

Decompisition

Death intentionally caused by another person is typically ruled a:

Homicide

Which is commonly fractured in strangulation cases?

Hyoid Bone

Toxicological specimens are taken at which stage of the death investigation:

Internal Examination

Evidence of tampering with the position of a body after the death can be obtained by evaluating the:

Livor Mortis

1. Algor Mortis

Lose of body heat Taking a core body temperature by inserting a thermometer probe into the liver Factors include: environmental conditions and body habitus (thin or fat) Loose 1-1.5 degrees Fahrenheit per hour until the body reaches the environmental temperature Estimates should be left to medical examiner

Homicide, suicide, accidental, natural and undetermined deaths are all categories of:

Manner of Death

What must a medical examiner possess?

Medical degree and Board Certification

The death of an individual suffering from chronic alcoholism is ruled:

Natural

By determining the oldest stage of fly found on body, they can determine _________ ________ ___ ________

Postmortem Interval of Death PMI

Time of death an be approximated by analyzing the vitreous humor and the levels of

Potassium

2. Livor Mortis

Settling of the pool of blood as the result of gravity in the small vessels of the circulatory system Purplish in color Dissipates NEVER (becomes fixed after 16 hours) Once "fixed" a change of body position will not result in alternation of the livor mortis patterns

On the 2nd day what else comes to the body?

Spiders, Millipedes and Mites

Rigor mortis refers to the:

Stiffness of death

Characteristics markings on the skin caused from the discharge of a firearm is known as:

Stippling/Tattooing

Partially digested or dissolved pills can be seen in the:

Stomach

Forensic Entomology

Study of insects and their relation to a criminal investigation The various insects involved in this activity have defined life cycles, which if properly noted may assist in defining the post mortem interval

The Autopsy

The examination of a body after death (aka postmortem examination) The goal of a forensic/medicolegal autopsy is to *determine the cause of death and confirm the manner of death*, often to be used in criminal proceedings

Estimated of the postmortem interval using entomological evidence must take into account

The geographical location, weather, locations climate over time

Post Mortem Interval

Time Since Death

The largest percentage of accidental deaths is due to:

Transport Accidents

Normal Putrefaction

Where the body breaks down naturally as a result of bacteria

Two Processes of Decomposition

*Autolysis* --- Fundamentally self digestion by cell's own enzymes *Putrefaction* --- Manifests in the abdomen (swelling, foul smell, black and blue discoloration, protrusion of eyes or tongue, slippage of skin)

A pathologist would expect rigor mortis to disappear after ____ hours

36

Beginning an hour after death, the body will loose heat at an approximate rate of:

1-1.5 F per hour

Types of Post Mortem changes in the body include:

1. Algor Mortis 2. Livor Mortis 3. Rigor Mortis 4. Decomposition

Once eggs have hatched it has been ___ hours since death

12

Lividy can be expected to fixed after _____ hours

16

Beetles come out after ___ - ___ hours

24-36 hours

T/F: Drowning is a Manner of Death

False

T/F: The rate of cooling of a dead body determine the Gender of Victims

False

A sharp force injury will most likely come from a:

Glass piece

Defense wounds are most typically seen on the:

Hands

What part of the victim's body is often bagged in order to prevent loss of trace evidence?

Hands

If the body is found covered with flies (not eggs), has no odor or other signs of decay, then the body:

Has been dead for LESS than an hour

3. Rigor Mortis

Results in the shortening of muscle tissue and the stiffening of body parts in the position at death Caused by chemical reaction in the muscles as they break down in death (stiffness of the muscles) Onsets within a couple hours in your jaw, small muscles or any body part under tension Appears after 2 hours, is at its greatest at 8-12 hours and after 36 hours it is fully dissipated

Which of the following techniques can be used to estimate the time of death?

Rigor mortis, eye fluid potassium levels, livor mortis