WARM UP #1 1/14

Investigators figure out the time of death (estimated) through different observations of the body. The following are some ways – see if you can figure out how they use it to find the time of death.

1. Insects2. Temperature of body3. Color of body4. Rigor mortis (what is it?)5. The eye6. Contents in digestive track

Ch 3 Notes #1TIME OF DEATH

Part 1: mortis

1/14

UNDERSTANDING WHAT HAPPENS TO THE BODY AFTER DEATH CAN HELP ESTABLISH TIME OF DEATH

Why establish the time of death?

To check the alibi , manner of death, and events of the crime

EX: fire – did they die

before or after the fire?

in water - drowned or killed first?

EX: Were was the person 8 hrs before?

How a forensic scientist/ pathologist estimates time of

death1. Find out when they

were last seen

2. Amount of rigor mortis

3. Livor mortis

4. Algor mortis stage

5. Degree of putrefaction

6. Amount of food in stomach and digestion

7. Vitreous humor amount

8. insects

RIGOR MORTIS – the stiffening of muscles after death

• RIGHT AFTER DEATH: muscles relaxed

• 3 HOURS later: stiffen head down

• 12 HOURS : whole body stiff

• 24 HOURS: starts to reverse

• 36 HOURS: rigor mortis is gone

Why muscles get stiff?

• LACTIC ACID buildup from lack of O2 in muscles

Why muscles become flaccid (relaxed)?

• Cells in the muscle break

down from enzymes

Cadaveric spasm – muscle rigidity (stiffness) right after

death.

Ex: clutching a weapon

LIVOR MORTIS – settling of blood after death

• Heart stops and blood stops moving

• Blood pools downward in body (toward the ground)

• ½ - 1 HOUR after death – skin reddish as blood moves out of vessels

• 6-10 HOURS - bruised look on side toward ground

• 10-12 HOURS after death “fixed” – blood no longer moves

How to tell if body moved after death

Bruised look is upward or on both sides

ALGOR MORTIS – decrease in body temperature after death

• Muscles make heat for our body: 98.6

• After death : muscles not working, so body cools

• 10-12” thermometer is placed into the abdomen in the liver area to take dead body temp.

                                        

Diagram showing how liver temperature, relative to room temperature, determines time of death. Since the temperature of a dead body falls at about one-and-a half degrees per hour, the 87 degree liver temperature indicates death at 6-7 hours before.

Body drops on average of 1.5 per hour

98.6 – dead body temperature = estimated time

1.5 of death

EXAMPLE

Body found at scene is 82.4. Approximately how long have they been dead?

98.6 – 82.4 = 16.2/1.5 = 10.8 hours 1.5 (.8 X 60min) = 48 min

10 hours 48 minutes

EXAMPLE 2

If the victim has been dead for 8 hours, what temperature would you expect the body to be?

98.6 - X = 8 98.6 – X = 8(1.5) 1.5 98.6 – X = 12 -98.6 - 98.6 - X = - 86.6 X = 86.6

Rate of cooling affected by:

1. Environment – climate2. Size of body3. Clothing and coverings4. Water or wetness5. Wind and humidity

* To be more precise, take temp and then temp one hour later to see the rate that it is going down (use this number instead of 1.5)