Estimating Time of Death

1. Estimating Time of Death

2. 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

3. 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

4. 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?

5. 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

6. 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

7. 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

10. @ 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

11. 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

12. Lividity Body on back – lividity along back and buttocks • 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

13. 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

14. 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

15. 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

16. Decomposition Rate Faster Slower • 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

17. Rate of Decomposition • Location of body is important: • 1 week exposed above ground • = 2 weeks in water • = 8 weeks in the ground

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. Blowfly Life Cycle 3rdinstar Pupa 2ndinstar Adult egg 1stinstar

26. Blowfly Life Cycle – pictures

27. 1stinstar Adult Pupa 2ndinstar Egg 3rdinstar

28. 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

29. 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 YES! …it’s very complicated Whaaaat?!?

30. 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

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