Forensic Science - Time of Death PDF

FORENSIC SCIENCE How old is the body? Time of Death Apply evidence to estimate the time of death Biological, Chemical and Circumstantial minutes to centuries appreciate the inherent uncertainty  Humans...

FORENSIC SCIENCE How old is the body? Time of Death Apply evidence to estimate the time of death Biological, Chemical and Circumstantial minutes to centuries appreciate the inherent uncertainty  Humans are warm-blooded creatures Time of Death & our metabolism maintains our body temperature & biochemical mechanisms After death muscles relax, body is limp - that maintain our temperature stop & body starts to cool: Algor Mortis our working & referred to this in Latin Different parts cool at different rates e.g brain faster than liver i as brain is closer to surfaced less insulated than I liver rectum or liver skin temperature is most unreliable bestparts to measure temperature Body cool at about General rule in1-1.5ºF/hour (about 0.6 – 0.8°C) after death May start to warm up after two days (putrefaction started) & generates heat Time of Death time of death ~ x = 1 to 1.5°F there are Algor mortis general rule 1-1.5ºF/hour Tn = T0 - xt (0.6 – 0.8°C) problems w this equ t = time in hours What is T0? Newton’s Law of Cooling about 37°C (98.6°F) but not exactly of cooling 36.5 - 37.5°C for healthy if the rate is ~ inde , 1 victim had a fever when proportional they were murdered , To will be to the Temperature of surroundings: higher temperature variable daytime hotter than nightine rate nence maybe > body T! [ , difference during As of cooling E day => not a linear uls but a curve other Clothing? Location? factors that Body size? Weather? effect e rate of cooling fi body : this provides us in an in precise estimate Time of Death: rigor mortis Lactic acid in muscle causes tension – Rigor Mortis L I and muscles , limbs all , become very stiff up to 36 hours after death jaw (2 hrs), these timings only are arms (4-6 hrs), guideline as there a other variables affecting legs (8-10hrs), are Rigor Mortis whole body (10-12hrs) muscles are affected smaller muscles before I larger Mortis : there is inprecise in Rigor  The Colour of the body discolouring due to gravity asI heart stops pumping a blood stops moving Settling of red blood cells due to gravity – Livor Mortis, post mortem lividity, hypostasis 0-12 hours : part of lower I body (depending Discolouration in lower parts. a on positi of e becomes can decipher body) colored Has the body been moved? darkly Yes for e ifI body is hanging, pig you will see liver mortis in e legs, Discolouration in lower parts. if lying down face , Parts on the ground not affected down livor mortis along , due to compression of the capillaries I front (contact flattening) of body I I BC cannot settle Mortis Melvor CO poisoning – cherry pink due to the carbon monoxide-haemoglobin complex Time of Death Only a best estimate from an expert Time of Death: other indicators Measuring + In a living inde ocular K levels in the ocular fluid , fluid has a lower + maintains it) (vitreous humor) 1rl (body increases after death & at Is will diffuse into : ocular fluid from I rest ofI body affected by , temperature Stomach and Intestine contents (time of last meal): stomach empties in about 2 hours & reconstruct last living actis of : person Look at the watch! Check mobile phone records and CCTV “Nowadays, last use of the telephone can be terribly important” Dr Nathaniel Cary, testifying in the trial of Stephen Wright  Body in qo has been dead for several days so e temp of body is I asi surrounding env vigor Time of Death: Putrefaction same , Mortis & livor Mortis has & come give break down to tissue ~ constituent molecules so we look e state of I body After death, your microorganisms start to eat you. This produces gases and characteristic smells. The rate depends heavily on local & factors such as temperature and also drug use. clothing ofe body whether read to is exposed I burried etc. , body body or starts swell , At the University of Tennessee-Knoxville “body farm” Time of Death: Putrefaction 2-3 days: staining begins on the abdomen. Body begins to swell due to gas formation. ~ veins start 3-4 days: staining spreads. Veins become discoloured to blister 5-6 days: abdomen swells with gas. Skin blisters 2 weeks: abdomen very tight and swollen. 3 weeks: tissue softens. Organs and cavities bursting. Nails fall off. 4 weeks: soft tissues begin to liquefy. Face becoming unrecognisable. A body without a coffin will be decayed within 12 years. In Singapore’s climate, can be two weeks!  ~ except to putrefacts dry wind dry out Mummification will to naturally body is preserved by mummified exposure , I body , dry body a will not putrefy) or done artificially) by administrate of diffe chemicals Rameses II V.I.Lenin Mao Tse Tung Jeremy Bentham Egypt Russia China University College, London Forensic Entomology their babies ~ so that Insects can arrive and lay eggs soon after death! have something watch to eat when they blowfly Need to know: species, life cycle, local conditions. Collect live maggots from the corpse and rear until adulthood. Then back calculate age and determine species. Blowflies and their life cycle forms of 3 maggots 7 1st instar ~ 2nd instar eggs 1 ~ 3rd instar adults M pupa C Peter Thomas 1964 Body found in the woods (Bracknell, Berkshire): covered in maggots: victim is Peter Thomas Police assumption: 6-8 weeks Simpson: “at least nine or ten days, not more than twelve”: & based on life cycle June 16 or 17th of maggots Prof. Keith Simpson  Peter Thomas 1964 Suspect: William Brittle Calliphora erythrocephalus Defense find three witnesses saying Thomas was alive on June 20th or 21st Defense call an entomologist (Prof McKeeny-Hughes) - who agrees with Simpson The Jury believes the maggots and not the eye-witnesses found quilty Danielle van Dam 2002 Put to bed evening of Feb 1st Reported missing morning of Feb 2nd Suspect David Westerfield desert trip Feb 2nd-5th under police surveillance from Feb 5th Body found Feb 27th in the mountains, badly decomposed, attacked by animals When did Danielle die; when was her body dumped?  Likely time of death according to Danielle van Dam forensic entomology and medical examiners January February 17 1 February 18 2 16 19 3 17 20 4 18 21 5 19 22 6 20 23 Faulkner 7 21 24 8 22 25 9 23 26 10 27 11 27 discovered 28 12 Rodriguez 29 13 Hall 30 14 Goff 31 15 Faulkner Haskell Medical Examiners Danielle van Dam ↑ ~ so many different inputs What went wrong? no accurate informat of Weather possibility f Microclimates in a particular area Covering of the body lost? Or is Westerfield innocent? Westerfield found guilty, sentenced to death by lethal injection Evidence of medical examiners plus one fingerprint, blood spot, hair from van Dam family dog in his vehicle crombinate of forensic evidence  Time of Death Skeletal remains Fluorescence: none indicates 100 years old or more not a measure of time of death ~ bores (FUN analysis) but tells whether I you from I same site are of same Bone nitrogen content fresh bone = 4% by weight age decreases with age (proteins breakdown) Hima & N leaks out into soil C Bone fluorine and uranium content of fresh bone = 0% increases with age (from ground water) ~ absorb F contains these 2 & v from elements water useful only for comparing samples from the same site ground because F and U in ground water/ minerals is variable  Piltdown Man Neanderthal man (Germany) Cro-Magnon man (France) Piltdown man (England) discovered 1912-15 claimed: 500,000 years old - small amounts of F (0.2%) little or no F nearly 4% nitrogen (modern orang-utan) theseI bores are not of I same age, Piltdown Man is a hoax ?  Carbon-14 dating bombarded init - 14C sprotons , queutrons nusable y is a radioactive isotope of William Libby carbon formed in the atmosphere (Nobel Prize 1960) by cosmic rays. The natural amount is constant and living things have C't form of CO2 , constant proport of this proportion of 14C. Radioactive atmosphere in is e in eair O2 in will have C & will be taken up by plants a passed atoms decay at a predictable rate. on to anything that eats those plants One half of 14C atoms will have decayed in 5568 years (the half life). Measure the amount of 14C and calculate back. CO2 dating dies if a plant/animal , it stops absorbing & I art of C in that creature's remains will then decay if you compare e art of IC in object of interest (proud its organic objects you will get a critical clock to work out time of death  it I standard method to obtain dates yo >500 is Carbon-14 dating ~ , Limitations – not very accurate for