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 Estimating Time of Death  Estimating Time of Death

Estimating Time of Death - PowerPoint Presentation

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Estimating Time of Death - PPT Presentation

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

death body time hours death body time hours water days temperature instar weeks amp decomposition lividity mortis stomach occurred

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Presentation Transcript

Slide1

Estimating Time of Death

Slide2

So…

Suspects can be eliminated and focus can be put on othersWhat can be used?Witness statementsBody temperatureRigor mortisLividityStomach contentsBugs on the body

Slide3

Defining 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

Slide4

Time 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?

Slide5

Measuring 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

Slide6

Body 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

Slide7

Rigor 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

Slide8

Slide9

Slide10

@ 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

Slide11

Fun 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

Slide12

Lividity

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

Slide13

Lividity 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

Slide14

2 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

Slide15

Putrefaction 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

Slide16

Decomposition 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

Slide17

Rate of Decomposition

Location of body is important:1 week exposed above ground = 2 weeks in water = 8 weeks in the ground

Slide18

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

Slide19

Other 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

Slide20

Adipocere 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

Slide21

Sinkers 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

Slide22

Bodies 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

Slide23

Stomach 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

Slide24

Getting 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

Slide25

Blowfly Life Cycle

egg

1

st instar

2nd instar

3rd instar

Pupa

Adult

Slide26

Blowfly Life Cycle – pictures

Slide27

1

st

instar

2nd instar

3rd instar

Egg

Adult

Pupa

Slide28

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

Slide29

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 lifeSO – corpse may have eggs, maggots, pupae, and adult blowflies present

Whaaaat

?!?

YES! …it’s very complicated

Slide30

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

Slide31

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