Transcript Forensic Science - McEachern High School

FORENSIC SCIENCE
Autopsy Procedures
WHAT’S LEFT?- ODD DAY
• Today- Autopsy procedures
• Tomorrow- Pig Autopsy
• Monday- Unit test
• Tuesday- performance assessment
• Wednesday- review
• Friday- Final exam
GETTING STARTED 12-10
• What is are 3 ways to determine
gender from skeletal remains?
AUTOPSY
• Postmortem examination of the body, including
dissection of the corpse
• Medical examiners are medical doctors who may also
be forensic pathologists..
• A forensic pathologist is a medical doctor who is trained
to identify why and how someone died & present those
findings to the court
• The primary goal of a medical examiner is to determine
cause and manner of death.
STEPS TO A DEATH INVESTIGATION
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Step one: preliminary investigation at the death scene
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Death investigator is employed by coroner/medical examiner’s office. Responsible for
initial assessment of body/death scene.
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Photographs and sketches body at scene
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Document any signs of trauma
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Make observations to help medical examiner make TOD determination
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Time between death and discovery: postmortem interval (PMI)
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At scene they look for obvious signs of decomposition
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Also look for scene markers- nonbiological evidence that provides clues to TOD
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Assessment of scene, collection of evidence, documentation and delivery to lab
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Death investigators also interview witnesses and victim’s family
STEPS TO A DEATH INVESTIGATION
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Step two: medical examination of body
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Assigned a case number, update chain of custody
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External examination: clothing, completes external examination, and X rays. Then
examined for any biological and nonbiological evidence.
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Autopsy- determine body temp, removes and examines the following structures: brain,
larynx, hyoid bone, heart and lungs.
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If a victim has been strangled, hyoid bone is usually broken
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Collects samples of blood, urine and bile.
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Then internal organs are removed and the mass of each is measured
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Stomach contents are analyzed
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Tissue samples are collected from various organs for DNA and toxicology screenings
Biological Evidence
Proper method of collection
Blood for DNA
Arterial blood collected from artery (femoral artery in leg)
Dried blood on victim: scraped off with scalpel or swabbed with
moist swab, then added to test tube for analysis
Semen
If sexual assault is suspected then swabs are taken of vagina,
rectum and inside mouth. Slides are then wiped and air dried for
further analysis
Hair
Placed in envelope. Control hairs from victim are collected as well
Tissue
each sample is placed in separate sterile container. Stored in
refrigeration until analysis can be completed
Fingernails
Victim’s fingernails are cut and each is placed in separate clean,
sterile envelopes to be analyzed for skin and other trace evidence
Bite marks
Swabbed for DNA, photographed and possibly a cast of bite mark
will be made. Bite marks may be excised along with some
surrounding tissue to be preserved
STEPS TO DEATH INVESTIGATION
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Step 3: Laboratory tests
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Toxicology- detection of drugs, alcohol and/or poisons
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Histology- study of tissues. Tissue is sliced very thinly, stained and studied under the
microscope for abnormalities
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Neuropathology- study of disease and trauma associated with the nervous system. More
than half of all deaths are associated with the nervous system, most often the brain.
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Serology- study of blood, semen and other bodily fluids
AUTOPSY REPORTS
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The medical examiner is responsible for all autopsy reports
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Responsible for testifying at court with relation to autopsy findings
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Parts of report
Heading: name, age, gender of victim
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External examination: all findings from external exam including diagrams. Includes overall
description of victim, full description of body
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Evidence of injury: external and internal injuries
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Internal examination: weighs and describes each organ noting any abnormalities
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Medical examiner’s findings and opinion: summarizes findings and gives his or her own
opinion