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 ID: 774746
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Slide1
Estimating Time of Death
Slide2So…
Suspects can be eliminated and focus can be put on othersWhat can be used?Witness statementsBody temperatureRigor mortisLividityStomach contentsBugs on the body
Slide3Defining Time of Death
Estimated – best guess as determined by medical examinerLegal – 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
Slide4Time of death continued…
Many deaths are not witnessed – occur in sleep, accidental, suicidal, homicideExample:If a serial killer kills a victim in July, but body isn’t found until OctoberWhat is the time of death?Physiological – took place in JulyLegal – October Estimated – could be July, or June or August?
Slide5Measuring Body Temperature – Algor Mortis
Normal temp is 98.6 degrees FahrenheitBody loses heat at a rate of 1.5 degrees per hourEventually reaches Ambient Temperature – the temperature of its surroundingsVaries depending on environment
Slide6Body temperature continued…
Liver temperature – reflects true core body temperatureIf body is found soon after death – more accurate time of death can be assessedWhat affects body temperature?ObesityClothingSurrounding temp.Exposure to sunlightEnclosed environment
Slide7Rigor Mortis
Stiffening of the body Loss of ATP from musclesProduction of ATP depends on supply of oxygen and nutrientsATP is needed to pull the actin & myosin fibers of the muscle apart; therefore, without oxygen, muscles remain contractedLost when heart stops Causes muscles to contract and stiffenRigor mortis ends when tissue begins to decompose
Slide8Slide9Slide10@ 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
Slide11Fun Fact: Cadaveric Spasm
Instantaneous onset of stiffness in the bodyLocked in exact posture it was in moment of deathTypically occurs under extremely violent physical or emotional circumstances
Slide12Lividity
Real corpses are less attractive than those portrayed in moviesDark, purplish discoloration of portions of the bodyCan help determine time of death, and if body was movedCaused by stagnation of blood in vessels
Body on back –
lividity along back and buttocks
Slide13Lividity continued
Color provides cluesRed or pink reveals high levels of oxygenCaused by carbon monoxide or cyanide poisoning, or cold temperaturesPurple color – poor oxygen levelsSevere heart failure, shock, or asphyxiaExample of how it’s used…Faint areas of fixed lividity along back, darker along the frontBody was laying on stomach and moved onto back after 4 to 6 hours
Slide142 processes – Decomposition
AutolysisSelf-digestion – enzymes of body begin a chemical breakdown of cells and tissuePutrefactionBacteria destroy the body’s tissueBacteria of intestinal tract and some environmental bacteriaThrive in warm & moist environmentsFreezing – stops activities of bacteria
Slide15Putrefaction is ugly & unpleasant
After 36 hours abdomen, neck, shoulders, and head take on a greenish colorBloating – accumulation of gas from bacteria – begins in faceSkin develops blisters where liquid or serum accumulateSkin begins to marble – reveals web-like pattern of blood vesselsAbdomen swells, skin continues to blister. Skin and hair begin to slip from body and fingernails start to slough offBody turns a greenish-black and fluids of decomposition leave through mouth and nose.As body swells tissues break open releasing gas and decomposition fluids
Slide16Decomposition Rate
ObesityExcess clothingHot & humidSepsis – blood infection can speed up so 24 hours = 5-6 days
ThinUnclothedCool surface/climateFreezing – can protect body for years
Faster
Slower
Slide17Rate of Decomposition
Location of body is important:1 week exposed above ground = 2 weeks in water = 8 weeks in the ground
Slide18Estimating 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
Slide19Other possibilities
MummificationBacteria can’t live in dry environmentsEgyptians used salt and spices to speed drying process so that bodies wouldn’t decayRemain in tact for long periods of time so estimating time of death is difficult, if not impossible
Slide20Adipocere Formation
Occurs in wet environmentsFound in water or warm & wet placesBody’s adipose (fat) tissue turns to soapWhite, greasy, waxy substanceTakes 3-6 months to formMutter Museum - Philadelphia
Slide21Sinkers to floaters
Body’s dumped in water:Initially sinkRise to surface when gases accumulate because of putrefactionTemperature of water greatly impacts processWarmer water will float after a few days, cooler water may take weeks or months
Slide22Bodies found in water display:
Swollen hands and face after 2-3 daysSeparation of skin from the body after 5-6 daysLoss of fingernails after 8-10 daysFloating after 8-10 days in warm water and 2-3 weeks in cold water
Slide23Stomach contents
Contents of victims stomach help determine T.O.DAfter meal stomach empties itself in 4-6 hoursFood is undigested – death occurred within 1-2 hours of eatingIf stomach is empty – death likely occurred several hours after eatingAlso, varies between people
Slide24Getting Buggy…
Bugs are usually predictable…But depends on geographic region, locale, time of day, & seasonEx: BlowflyShows up within the first hourSeek moist areas of corpse to lay eggsNose, mouth, armpit, groin and open wounds favoredEggs hatch to larvae (maggots) with 24 hoursWithin 12 days adult flies emerge
Slide25Blowfly Life Cycle
egg
1
st instar
2nd instar
3rd instar
Pupa
Adult
Slide26Blowfly Life Cycle – pictures
Slide271
st
instar
2nd instar
3rd instar
Egg
Adult
Pupa
Slide28How 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
Slide29What 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 lifeSO – corpse may have eggs, maggots, pupae, and adult blowflies present
Whaaaat
?!?
YES! …it’s very complicated
Slide30Other 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
Slide31Using a combination of these methods will help to best determine the most accurate time of death.