Time of Death:

During an autopsy, the forensic examiner wants to determine when the person died.

Time of death can:

Prove innocence based on time and place or add interest

Many factors are used to approximate the time of death

• Livor Mortis: Lividity (Purple color)• Rigor Mortis (stiffness)• Algor Mortis (loss of temp)• Environment: ambient temp,humidity, wind• Clothing• Exercise• Weight • Decomposition of Eye?

Livor Mortis means death color

As a body decomposes, blood seeps down through the tissues and settles into the lower parts of the body.

RBC begin to break = spilling contents

Hemoglobin turns purple when outside of RBC

Purple color is visible on skin where blood pools

Lividity: the pooling of blood provides a clue as to how long the person has been deadFirst begins 2 hrs after deathDiscoloration becomes permanent after 8 hours

If death occurred between 2 and 8 hrs lividity will be present but if the skin is pressed the color will disappear

After 8 hours, lividity remains

Ambient Temperature at death impacts the time it takes for lividity to set in

Faster = hot Slower = cold

**** important to note environmental condition surrounding body

Livor mortis provides clues in addition to time of deathPosition of corpse in the first 8 hoursReveal if the body has been moved

Dual lividity: Ex. Person died sitting in a chair: lividity on back of thighs, buttocks and bottom of feet (in first 8 hours)Then the corpse is moved face down on the floor: lividity on face, chest and abdomen and front surface of legs

Tight watches or belts affect livor mortis = impede blood flow

-Starts within 2 hours-Starts in the head working down to the legs-After 12 hours, most rigid state-After 24-36 hours gradually lose stiffness due to acid formation (degradation) -Rigidity in face and neck: recent (2 hrs)-Body is rigid but not in face then over 15 hrs

-If a body shows no rigor death occurred less than 2 hours or more than 48

Rigor also depending on the condition of the body at death and on factors in the atmosphere, particularly temperature.

Rigor Mortis: temporary death stiffness

Stiffness = 1. level of ATP dropping. 2. myosin binds to actin and

the muscles contract.

3. However, with no ATP to reset the crossbridges and release the myosin

4. Due to Ca2+ accummulation

Molecular chemistry - STIFF

Muscles eventually relax when apoptosis occurs (autolysis)

Cell dissolves

Many factors affect When rigor mortis sets in and how long it lasts

1. Ambient temperature: cooler = slower

2. Weight: body fat stores extra O2 slows down rigor

3. Type of clothing: s keep body warm = accelerates rigor

4. Illness: fever: accelerates rigor, hypothermia: slower

5. Level of physical activity shortly before death: exercise, struggling speeds up rigor

a. body temp b. less O2 c. increase in lactic acid

6. Sun exposure: increase rigor

Algor mortis: “death heat”• Temperature loss in a corpse• Insert a thermometer into the corpse’s liver• ~ 1 hr after death

• Body cools at a rate of 0.78 oC (1.4oF) per hour

• ~ After the first 12 hours• Body cools at a rate of 0.39 oC (0.7oF) per hour• Continues until reaches ambient temp of enviro.

• ~ Environment affects rate of temp loss as well

• Temp, Wind, excess body fat, clothing

Rule of thumb estimate: lose 1 degree/hour for a range

Stomach and Intestinal Contents

• 4 – 6 hours for the stomach to empty contents into S.I.

• Another 12 hours for food to leave the S.I.

• ~24 hours for a meal to be eaten and undigested food leaves the L.I.

1. Undigested contents in stomach: death <2 hours after last meal

2. Stomach is empty , food in S.I: death at least 4 – 6 hours after meal

3. Empty SI but wastes are in L.I. then death occurred > 12 hours

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