Forensics Lab #1: Forensic Bones

The Role of the Forensic Pathologist Serve as the medical examiner/coroner To answer several basic questions – Who is the victim? – What injuries are present? – When did the injuries occur? – Why/How were the injuries produced? Determine the cause of death – Perform an autopsy to determine cause if death is suspicious or unexplained

Death is classified as one of the following depending on t he circumstances: Natural Homicide Suicide Accident Undetermined

Estimating Time of Death (TOD) Several stages of decomposition ME uses the information based on the stage of decomposition to estimate TOD

Major Stages of Decomposition Rigor mortis – Stiffening of the muscles – Body becomes rigid – Begins within 24 hours of death but disappears after 36 hours Livor mortis – Results in the settling of blood in areas of the body closest to the ground (due to gravity and loss of blood pressure) – Happens within 12 hours – Does not happen if body is restricted by clothing, moved to a different location, etc.

Major Stages of Decomposition continued… Algor mortis – The body temperature continually cools until it reaches ambient (room/location) temperature – Rate of heat loss can be affected by such factors as location, size of the body, weather conditions, etc. – This method can only provide an estimate of TOD – General rule: beginning ≈ 1 hr after death, heat loss is ≈ 1-1½°F/hr until body reaches the environmental temperature of where it is located

Major Stages of Decomposition continued… Ocular Fluid Analysis – Determine potassium (K) levels in the vitreous humor (fluid within the eyeball) – Cells within the inner surface of the eyeball release K into the fluid – Amounts of K can be analyzed at different intervals after death to determine the rate at which the K is being released and estimate TOD based on the rate of K release

Forensic Anthropology: Skeletal Detectives ID and examination of human skeletal remains Bones are durable and break down slowly Bones may reveal information about the owner such as age, sex, race, diseases, injuries, etc. Facial reconstructions may also be possible and a composite drawing made

Forensic Entomology: Testimony of Insects The study of insects and their relation to a criminal investigation Presence of insects/larvae can be used to estimate TOD Blowflies are the first insect to infest a body – Eggs hatch into larvae/maggots – Consume human organs/tissues – Types of insects identified and stage of life cycle used to estimate TOD – Life cycle affected by environmental conditions which must be considered when estimating TOD

Life Cycle of the Blowfly

Key Points An autopsy is normally performed if a death is suspicious or unexplained. Rigor mortis occurs after death and results in the stiffening of body parts in the position they are in when death occurs. Livor mortis occurs after death and results in the settling of blood in areas of the body closest to the ground. Algor mortis refers to postmortem (after death) changes that cause a body to lose heat. Forensic anthropology is concerned primarily with the identification and examination of human skeletal remains. A forensic entomologist studies the development of insect larvae in a body to estimate time of death (TOD).

Source: Saferstein. Richard. Forensic Science: An Introduction. Upper Saddle, New Jersey,: Pearson Education, Inc., 2008