ESTIMATING TIME OF DEATH

So…

Suspects can be eliminated and focus can be put on others

What can be used?

Defining Time of Death

Estimated –

Legal –

Physiological –

Time of death continued…

Many deaths are not witnessed – occur in sleep, accidental, suicidal, homicide

Example: If a serial killer kills a victim in July, but body

isn’t found until October

What is the time of death? Physiological – took place in July Legal – October Estimated – could be July, or June or August?

Measuring Body Temperature

Normal temp is _?_ degrees Fahrenheit Body loses heat at a rate of _?_ degrees per

hour Eventually reaches _?_– the temperature of

its surroundings Varies depending on ? ? ?

Body temperature continued…

?_ – reflects true core body temperature What affects body temperature?

Rigor Mortis

Production of ATP depends on supply of oxygen and nutrients ATP is needed to pull the actin & myosin fibers of

the muscle apart; therefore, without oxygen, muscles remain contracted

Lost when heart stops Causes muscles to _?_

Rigor mortis ends when tissue begins to ?

@ Temp of 70 degrees F

_________after death rigor mortis is detectable

Entire process takes _____________to peak After _?_ hours all muscles relax

Least effective method of determining time of death because it is extremely variable

Fun Fact: Cadaveric Spasm

Instantaneous onset of stiffness in the body

Locked in exact posture it was in moment of death

examples?

Lividity

Dark, purplish discoloration Can help determine time of

death, and if body was moved

Body on back – lividity along back and buttocks

Lividity continued

Color provides clues

Caused by carbon monoxide or cyanide poisoning, or cold temperatures

Severe heart failure, shock, or asphyxia

Example of how it’s used… Begins ? Hours after death Becomes permanent _?_ hours after death

2 processes – Decomposition

_?_ – enzymes of body begin a chemical breakdown of cells and tissue

Bacteria destroy the body’s tissue

Bacteria of intestinal tract and some environmental bacteria

Thrive in warm & moist environments Freezing – stops activities of bacteria

Putrefaction is ugly & unpleasant

After 36 hours abdomen, neck, shoulders, and head take on a greenish color

Bloating – accumulation of gas from bacteria – begins in face

Skin develops blisters where liquid or serum accumulate

Skin begins to marble – reveals web-like pattern of blood vessels

Abdomen swells, skin continues to blister. Skin and hair begin to slip from body and fingernails start to slough off

Body turns a greenish-black and fluids of decomposition leave through mouth and nose.

As body swells tissues break open releasing gas and decomposition fluids

Rate of Decomposition

Location of body is important: 1 week exposed above ground

Estimating time of death

After a few weeks can be extremely difficult Body temperature, rigor mortis, lividity no

longer are of any use Postmortem decay timeline is modified

according to conditions

Other possibilities

Mummification Bacteria can’t live in dry environments Egyptians used _? to speed drying process

so that bodies wouldn’t decay Remain in tact for long periods of time so

estimating time of death is difficult, if not impossible

Sinkers to floaters

Body’s dumped in water: Rise to surface when gases accumulate

because of putrefaction Temperature of water greatly impacts process

Warmer water will float after a few days, cooler water may take weeks or months

Bodies found in water display: Swollen hands and face Separation of skin from the body Loss of fingernails after Floating after 8-10 days in warm water

and 2-3 weeks in cold water

Stomach contents

Contents of victims stomach help determine T.O.D

Food is undigested – death occurred

within 1-2 hours of eating If stomach is empty – death likely

occurred several hours after eating

Also, varies between people

Getting Buggy…

Bugs usually predictable…But depends on geographic region, locale, time of day, & season

Ex: Blowfly Nose, mouth, armpit, groin and open wounds

favored Eggs hatch to larvae (maggots) with 24 hours Within 12 days adult flies emerge

Blowfly Life Cycle

egg

1st instar

2nd instar

3rd instarPupa

Adult

Blowfly Life Cycle – pictures

1st instar

2nd instar

3rd instar

Egg

Adult

Pupa

How can this be used?

Find only eggs –

Fully grown maggots, but no pupae – death occurred less than 10 days earlier

Finding pupa indicates that 6-10 days have passed Circumstances can throw off this schedule:

Extremely cold conditions – may go dormant

Ex: if body is warm during day and cool at night maggots may go through lifecycle during the hot times

Entomologist may consult climotologist

What if someone is dead for 3 weeks?

Why would this be complicated? Adults produced after ~2 weeks SO – corpse may have eggs, maggots,

pupae, and adult blowflies present

Whaaaat?!?

YES! …it’s very complicated

Other evidence to estimate T.O.D Broken watch Victim who missed work for 2 days and

is found near his or her front door, dressed in work attire, holding keys, probably heading to work at time of death

Victim never showed for a scheduled racquetball game and was found in the garage in exercise clothes likely died while leaving for game

Conclusion