2The Medical ExaminerThe Medical ExaminerVs.The Coroner
3The Medical ExaminerThe Medical Examiner is a medically qualified governmentofficer whose duty is to investigate deaths and injuries thatoccur under unusual or suspicious circumstances, and toperform post-mortem examinations.The Medical Examiner is required to have a medical degree,often with additional education in forensic pathology.Typically, The Medical Examiner is appointed to his/herposition.The Medical Examiner’s task is to determine cause, timeand manner of death.
4The Medical ExaminerThe Coroner are often elected (rather than appointed) officials,and usually do not need to hold any medical qualification.As finders of facts, they use Medical Doctors to determinecause, time and manner of death.
5The Medical ExaminerWhat are some of the questions a M.E. is asked to answer?The reason someone dies is called Cause of Death.Ex. Heart attack, disease, stroke, physical injury.2) The way someone dies is called Manner of Death.Natural Causesb. Accidental Deathc. Suicided. Homicidee. Unknown
6The Medical Examiner 3) Identification In some cases it is not obvious who the victim is. It isthe M.E. job to I.D. the victim.The M.E. will use many of the following to determineI.D.
7The Medical Examiner Dental Impressions DNA Skeletal Remains Can you think of any other meansof identification?
8The Medical Examiner 4) Time of Death During an autopsy, the M.E. wants to determine when theperson died.By establishing time of death, a suspect may be proveninnocent simply because he/she was not in the same placeas the victim at the time of death.On the other hand, a suspect may remain a person ofinterest if he/she was in the same area at the time ofdeath.
9The Medical Examiner How is the time of Death Established? 1) Livor Mortis= Death ColorWhen the heart stops beating blood will settle or pool inthe lowest parts of the body.
10The Medical ExaminerPooling of blood in the body, known as lividity, willprovide clues to how long the person has been dead.Determining time of Death with the use of Lividity.Lividity begins to show about two hours after death.Discoloration is permanent after about eight hours.Between two and eight hours, if the skin is pressed,the color will disappear.After eight hours, if the skin is pressed, the color willremain.
11The Medical ExaminerBesides Time of Death, lividity can provide other clues.Because gravity pulls blood toward the ground, livididtycan reveal the position of the body at the time of death.
12The Medical Examiner 2) Rigor Mortis = Death Stiffness Rigor Mortis is the temporary stiffness of the body afterdeath.Determining time of Death with the use of Rigor Mortis.Rigor Mortis starts about two hours after death.Rigor Mortis starts at the head and works its way to the legs.After 12 hours the body is at it stiffest state.Generally, stiffness gradually disappears after hours.
13The Medical ExaminerSuppose a detective comes to a crime scene and thevictim’s body is not in rigor. What is the time of death?Answer: Less than 2 hours or more than hours.Suppose a detective comes to a crime scene and thevictim’s body is in full rigor. What is the time of death?Answer: Around 12 hours.
14The Medical Examiner 3) Algor Mortis = Death Heat Algor Mortis is the cooling of the body after death.Determining time of Death with the use of Algor Mortis.Determining time of death using the cooling of thebody (taken from the liver) is sometimes difficult.Many factors contribute to how the body cools. Such as:Environment TempVictim’s clothes, if anyVictim’s Weight
15The Medical ExaminerDetermining time of Death with the use of Algor Mortis.0 – 12 hr after death12 – ? hr after deathBody loses 1.4° F per hrBody loses .7° F per hrThese values are just estimates and my vary dependingupon many other factors.We can average these values and use 1° F per hour.
16Answer: Since the body cools at a rate of 1° F, 6 hrs. The Medical ExaminerDuring an autopsy the liver temperature is determinedto be 92.6° F. Approximately how long has the body beendead?98.6° F – 92.6° F = 6° FAnswer: Since the body cools at a rate of 1° F, 6 hrs.
17The Medical Examiner 4) Stomach Contents In general it takes four to six hours for the stomach toempty its contents into the small intestines.It then takes another 12 hours for the food to leavethe small intestine.It takes about 24 hours for food to complete thethe digestion cycle.
18The Medical Examiner From this information it can be concluded that: If undigested food is present in the stomach, thendeath occurred zero to two hours after the last meal.2) If the stomach is empty but food is found in the smallintestine then death occurred at least four to six hoursafter a meal.3) If the small intestine is empty but food is found in thelarge intestine, death occurred 12 hours or more after ameal.
19The Medical Examiner 5) Decomposition A corpse decomposes in predictable ways over time thatcan help determine time of death.Within two days after death:Cell autolysis (self digestion) beginsSkin turns green/purple from blood decomposition
20The Medical Examiner After four days: Skin starts to blister The abdomen swells with gas released from bacteriain the intestines.Within six to ten days:The build up of gases cause chest and abdomen toburst.Fluids begin to leak from the body openings.Eyeballs and tissues begin to liquefy.The skin sloughs off the body.
21The Medical Examiner 6) Insects The presence of insects on a body can provide detailedinformation about the Time of Death.In fact, insects are so useful in crime scene investigationThat there is an entire field dedicated to this study andPractice and it is called Forensic Entomology.
22The Medical ExaminerWithin minutes of death, certain insect arrive to lay theireggs on the body.For example, blowflies lay their eggs which soon turn intolarva. The larva feed on the decomposing flesh.Sometime after, wasps lay their larva on the body whichfeed on the blowfly larva.In addition, each stage of decomposition attracts differentinsects.
23The Medical ExaminerLet’s look at the Blowfly and how it can help us determineTime of Death.
24The Medical ExaminerSimilar to other insects, blowflies exhibit different stagesof development:EggsLarva
26The Medical ExaminerBecause we know how long it takes for the various stagesof development, forensic entomologists can determinewhen the blowflies arrived by studying the insects on thecorpse.If we know when they arrived we can determine approximatetime of death.
27The Medical Examiner Blowfly Life Cycle Stage Size (mm) When first appearsPhase DurationCharacteristicsEgg2Soon after death8 hrsFound in moist areasLarva52 – 5 days20 – 56 hrsBlack mouth visiblePupae10-178 – 20 days4 – 12 daysImmobileAdultVaries21 – 24 daysSeveral WeeksFlight possible
28The Medical ExaminerIf a corpse contains blowfly eggs approximate time ofdeath is?Answer: Less then 24 hrsIf a corpse contains blowfly larva approximate time ofdeath is?Answer: Between 2 and 5 days.If a corpse contains blowfly pupae approximate time ofdeath is?Answer: Between 18 and 24 days.