Estimating Time of Death2

8/19/2019 Estimating Time of Death2

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Estimating Time of Death

Forensics 2014-1015


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Livor Mortis”Death Color”

• As body begins to decom ose blood see s do!n thro"ghtiss"es and settles in lo!er arts of body – #ed $lood Cells T"rn "r lish-bl"e

• %ooling of blood & lividity• 'i(idity $egins abo"t 2 ho"rs after death• $et!een 2-) ho"rs li(idity !ill be resent* b"t if the s+in

is ressed color !ill dissa ear• After ) ho"rs li(idity remains if the s+in is ressed• Ambient Tem erat"re & Tem erat"re s"rro"nding body

– a,ects the rate of li(idity• igher Tem erat"re & .ncrease in rate of li(idity

• 'o!er Tem erat"re & Decrease in rate of li(idity


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Livor Mortis

• /hat else can be determined fromli(idity –

%osition of body follo!ing death – /hether a body has been mo(ed ostmortem


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Algor Mortisdeath heat

• The Chill of Death – Algor ortis-Describes tem erat"re loss in a

cor se• #ate of loss in "enced by en(ironmental conditions

– E3terior tem s – Clothes (s no clothes ect

– First 12 ho"rs• Tem erat"re loss & 6) degrees Celsi"s 71 4 degrees

Fahrenheit8 er ho"r – After 12 ho"rs

• Tem erat"re loss & 9: degrees Celsi"s 7 6 degreesFahrenheit8 er ho"r


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"scle Fibers andContraction


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Rigor Mortis“Death Sti ness”

• Normal Muscle Contraction – Calci"m released from membranes inside cell ca"ses m"scle ;bers cells to

contract – Acti(e trans ort then remo(es calci"m so m"scle ;bers can rela3

• This re


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Rigor Mortis

Observation

The body is at its most rigidstate

No visible signs of rigor

Stiffness generallydisappears

Approx. Time Scale

Just over 2 hours

Less than 2 hours or more than 48 hours ago

After ! hours


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,actors A ecting Rate of Rigor

• Am&ient Tem'erature – Cold- slo!s rigor – /arm- Accelerates #igor

• Clothing or Lac# of Clothing – Clothes & accelerates rigor – >o Clothes & slo!s rigor

• Sun -.'osure – Accelerates rigor

• Activity/-.ercise – E3ercising or str"ggling & accelerates rigor – =lee & slo!s rigor

• 0ody 1eight – ?bese- slo!s rigor 7fat stores o3ygen8 – Thin- Accelerates #igor


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Stomach and 2ntestinalContents

• .f undigested stomachcontents are resent* thendeath occ"rred 3 to ! hoursafter last meal

• .f the stomach is em'ty &utfood is found in the smallintestine * then death occ"rredat least *4) hours after lastmeal

• .f the small intestines isem'ty and !astes are fo"nd inlarge intestine* then death

robably occ"rred %! or morehours after last meal


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Decom osition

• The rotting or brea+ do!n of alltiss"es and organs – $acteria and other microorganisms aid

the decom osition rocess* @"st as theydecom ose lants and animals in theen(ironment

• ?cc"rs in %redictable %attern – Can be "sed to hel determine Time of

Death


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Stages of Decom'osition• 2nitial Decay

– Cor se a ears normal from the o"tside* b"t is starting todecom ose from the actions of bacteria and a"tolysis

• "utrefecation

– ?dor of decaying esh is resent and the cor s e a earss!ollen• 0lac# "utrefecation

– ery =trong odor %arts of the esh a ear blac+ Basesesca e and the cor se colla ses

• 0utyric ,ermentation – Cor se is beginning to try o"t ost of the esh is gone

• Dry Decay – Cor se is almost dry F"rther decay is (ery slo! from lac+ of

moist"re


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Timeline of -vents duringDecom'osition

• 1ithin ! days after death5 – Cell A"tolysis begins follo!ing death – Breen and "r lish staining occ"rs form blood decom osition – The s+in ta+es on a marbled a earance – The Face $ecomes discolored

• After * Days5 – The s+in blisters – The abdomen s!ells !ith the gas carbon dio3ide release by

bacteria li(ing in the intestines• 1ithin )4%3 Days5

– Cor se bloats !ith carbon dio3ide* e(ent"ally gas ca"ses the chestand abdominal ca(ities to b"rst and colla se – Fl"ids begin to lea+ from body o enings as cell membranes r" t"re – Eyeball and other tiss"es li


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Factors A,ecting #ate ofDecom osition

• Tem erat"re – $odies decom ose fastest !ithin 21-96 degrees Celsi"s 760-

:: degrees Fahrenheit8 – $elo! this range rate decreases beca"se cold tem erat"res

slo! the gro!th of bacteria and microorganisms – Abo(e this range tends to dry o"t cor ses and reser(e them

• =e(eral other factors – .llness

– Age – /eight – Clothing or 'ac+ of Clothing


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,orensic -ntomology• ,orensic entomologist

– Collects insect e(idence from on* abo(e* and belo!the body

– #ecords en(ironmental conditions – $eca"se life cycles are a,ected by "ct"ations in

the daily en(ironmental conditions* insects cannotro(ide an e3act time of death* only a close

estimate

– At crime lab some of the insects are raised "nderen(ironmental conditions that mimic theen(ironmental conditions at the crime scene toobtain most acc"rate a ro3imation


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,orensic -ntomology

• $lo! ies are "s"ally the ;rst insects toarri(e at a dead body – s"ally arri(e !ithin min"tes

• $lo! ies e3hibit di,erent life stages – Egg* lar(a 7also +no!n as instars8* " a*

re " a* ad"lt


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-gg

• Soon after Death6&lo 7y eggscan &e found in the moist$ armareas of a cor'se – 8 + hrs


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Larva Stages %92nstar %:

• Within 20 hours


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'ar(a 27.nstar 28

• After ! ; days


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Larva Stage (92nstar (:

• After 4-5 da s


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"re4"u'a

• After +4%! days


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"u'a

• After %+4!* days


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Adult

• After !%4!* days


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Time of Death62nsects

o The inse"t life "y"le provides s"ientists #ith aben"hmar$ to estimate a time of death

o %nse"t eviden"e "annot provide an e&a"t time ofdeath'flu"tuating environmental "onditions

o %nse"t eviden"e provides a "lose estimate

Estimating Time of Death2

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