1. Forensic Medicine
Autopsy

2. Methods to determine time of death
Traditional indicator:
Rigor mortis
Begins 3 hours after death in face and eyelid muscles
Takes 12 hours to affect entire body, going from “head to toe”
Process reverses after 36 hours and decaying sets in if body is not cooled to 38 degrees F

3. Rigor Mortis
To police, medical examiners, and lawyers in the criminal justice system, rigor mortis has much more significance.
It's a clue to understanding the circumstances of someone's unexpected -- and possibly violent -- death.
Rigor mortis is a piece of the forensic jigsaw puzzle, and combined with other details, it can help detectives and medical examiners figure out what happened.

4. Lividity (hypostasis)
The process through which the body's blood supply will stop moving after the heart has stopped pumping
Visible minutes after death
Red cells begin to settle (in direct response to gravity) and skin turns red or dark purple
In 6-10 hours, color becomes permanent; Only up to the first six hours of death can lividity be altered by moving the body.
Also referred to as Livor Mortis or Post Mortem Hypostasis.

5. Continued…
For example an individual found lying on their stomach would be found with all the blood from their back heading towards the ground.
Any part of the body which has come into contact with a firm surface for a period of time, such as a floor or bench top, will show signs of lividity as this impression against the skin displays itself as an indentation surrounded by gravity-pulled blood.

6. Body Temperature
Falls at a rate of 1 degree per hour; can be used to give the officers at the scene a rough idea as to how long the deceased has been dead.
At the scene of a crime the pathologist, who will be charged with initially examining the body in its discovered post mortem condition, will take the body's temperature in any way appropriate.
Obesity, clothing, and warm environments slow cooling

7. Please note:
None of these methods are totally reliable and can be manipulated
But still valuable information to police and pathologists