ESTIMATING TIME OF DEATH

So…  Suspects can be eliminated and focus can be put on others  What can be used?  Witness statements  Body temperature  Rigor mortis  Lividity  Stomach contents  Bugs on the body

Defining Time of Death  Estimated – best guess as determined by medical examiner  Legal – the time the body was discovered and pronounced dead (this time is recorded on the death certificate)  Physiological – the time the victim’s vital functions actually ceased

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 – Algor Mortis  Normal temp is 98.6 degrees Fahrenheit  Body loses heat at a rate of 1.5 degrees per hour  Eventually reaches Ambient Temperature – the temperature of its surroundings  Varies depending on environment

Body temperature continued…  Liver temperature – reflects true core body temperature  If body is found soon after death – more accurate time of death can be assessed  What affects body temperature?  Obesity  Clothing  Surrounding temp.  Exposure to sunlight  Enclosed environment

Rigor Mortis  Stiffening of the body  Loss of ATP from muscles  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 contract and stiffen  Rigor mortis ends when tissue begins to decompose

@ Temp of 70 degrees F  2 hours after death rigor mortis is detectable  Entire process takes 8 to 12 hours to set in  Remains fixed for another 18 hours  After another 12 hours muscles relax  Therefore can be useful in determining time of death during the first 36 to 48 hours  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  Typically occurs under extremely violent physical or emotional circumstances

Lividity  Real corpses are less attractive than those portrayed in movies  Dark, purplish discoloration of portions of the body  Can help determine time of death, and if body was moved  Caused by stagnation of blood in vessels

Lividity continued  Color provides clues  Red or pink reveals high levels of oxygen Caused by carbon monoxide or cyanide poisoning, or cold temperatures  Purple color – poor oxygen levels Severe heart failure, shock, or asphyxia  Example of how it’s used…  Faint areas of fixed lividity along back, darker along the front Body was laying on stomach and moved onto back after 4 to 6 hours

2 processes – Decomposition  Autolysis  Self-digestion – enzymes of body begin a chemical breakdown of cells and tissue  Putrefaction  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

Decomposition Rate  Obesity  Excess clothing  Hot & humid  Sepsis – blood infection can speed up so 24 hours = 5-6 days  Thin  Unclothed  Cool surface/climate  Freezing – can protect body for years FasterSlower

Rate of Decomposition  Location of body is important:  1 week exposed above ground  = 2 weeks in water  = 8 weeks in the 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 salt and spices 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

Adipocere Formation  Occurs in wet environments  Found in water or warm & wet places  Body’s adipose (fat) tissue turns to soap  White, greasy, waxy substance  Takes 3-6 months to form  Mutter Museum - Philadelphia

Sinkers to floaters  Body’s dumped in water:  Initially sink  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 after 2-3 days  Separation of skin from the body after 5-6 days  Loss of fingernails after 8-10 days  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  After meal stomach empties itself in 4-6 hours  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 are usually predictable…But depends on geographic region, locale, time of day, & season  Ex: Blowfly  Shows up within the first hour  Seek moist areas of corpse to lay eggs  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 1 st instar 2 nd instar 3 rd instar Pupa Adult

Blowfly Life Cycle – pictures

1 st instar 2 nd instar 3 rd instar Egg Adult Pupa

How can this be used?  Find only eggs – death occurred less than 4 hours earlier  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:  Don’t deposit eggs at night  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 climatologist

What if someone is dead for 3 weeks?  Why would this be complicated?  Adults produced after ~2 weeks  …Lay their own eggs  …Follow a similar pattern of life  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

 Using a combination of these methods will help to best determine the most accurate time of death.