Death Investigation

Medical examination Case number, chain of custody Thorough exam of body - to determine mechanism, manner, and cause of death Cause = immediate reason (ex. fall) Mechanism = body’s physiological response that ended life (ex. Bled to death)

External Exam View clothing, body, & order Xrays Look for & process evidence on body - biological (hair, blood, etc) - nonbiological (glass, soil, fibers)

Autopsy Body temp – normal = 37o C - at death, temp cools = algor mortis Measure with thermometer into liver Temp falls ~1.5oF per hour until reaches ambient temp

Time of Death: if w/in 1st 12 hours: Time since death = 37oC - current body temp 0.78 Or, time since death = Normal body temp(F) – Current body temp 1.4

If after 12 hours – clues: - extremities cold 1st 12 hours – body temp decreases 9.4 oC, so… if below 27.6oC, then more than 12 hours Formula: 27.64oC – Current Temp + 12 0.39

Several factors affect algor mortis (ex. Temp where person died) Therefore, only get an estimation of time of death

Structures to Study Brain, larynx, hyoid bone, heart, lungs Hyoid – if broken, strangled Body fluids – blood, urine, bile Remove and record mass of internal organs Stomach contents – clues for TOD If decomposing, get tissue from several organs for DNA analysis and tox screen

Blood for DNA Semen Hair Figure 8-8. Processes for collecting biological evidence. Biological Evidence Proper Method of Collecting Evidence Blood for DNA If the victim is unidentified, the medical examiner collects blood from an artery, such as the femoral artery in the thigh, and places it on a blood card. This card is sent to the DNA lab for identification. If dried blood is found on the victim's body, it might have come from the perpetrator. Using a scalpel, the examiner removes the dried blood from the skin and places it in a test tube. If there is too little dried blood on the skin to use a scalpel, the examiner uses a swab moistened with saline solution. The swab must be air dried before the examiner places it in a sterile test tube. Semen If the medical examiner suspects that the victim was sexually assaulted, he or she places cotton swabs inside the vagina and rectum. The examiner removes the swabs and makes slides of the evidence. The slides and swabs are air dried. The examiner then packages and labels the slides and swabs. The examiner also swabs the mouth around the gums and teeth. Moist, sterile gauze is used to collect any additional suspicious material in the mouth. The gauze is then air dried and placed in a test tube, envelope, or bag. Hair The examiner collects hair from the victim's body and places it in an envelope. The origin of the hair is unknown—some may belong to the perpetrator; some may belong to the victim. The examiner documents where the hair was collected. He or she also collects control hairs from multiple areas of the body. The control hairs must be pulled from the root to get the follicular tag so that DNA analysis can be performed. These control hairs are compared to the hairs of unknown origin to determine whether the unknown hairs are consistent with the victim's hair. In rape cases, the pubic hair is combed for hairs not belonging to the victim.

Tissue Fingernails Bite Marks The examiner places each tissue sample in a separate sterile container. Tissue samples are stored in a cool area, such as a refrigerator, to await further examination. Fingernails If the examiner finds loose pieces of fingernail on the body, he or she collects them and places them in an envelope. The examiner then cuts the victim's fingernails and places each cut fingernail into its own clean, sterile envelope. The envelopes are labeled with the location of the fingernail, such as "right index finger." Bite Marks A forensic odontologist is a doctor trained to examine dental records and bite mark patterns during a criminal investigation. If one is available, a forensic odontologist will examine any bite marks prior to the autopsy, before the body is cleaned. If an odontologist is not available, the medical examiner will wipe the bite mark with a cotton swab moistened with saline and then with a dry swab. Both are air dried and placed in test tubes. This technique collects saliva around the wound. The saliva may contain DNA. The medical examiner will also take pictures of the wound with a ruler in the field of view. If the materials are available, the examiner will make a cast of the bite mark.

Non-Biological Evidence Bullet removal – gloved hand or rubber-tipped tool; placed in labeled envelope (inc. area of body) Surgical equipment – ex. Pins, rods – have serial #