jimtrue.com : school : CJT1110 : CH16: Homicide Investigation Pt 1
Posted by Jim True on April 14, 2003 6:00 AM. Last Updated October 22, 2006 9:23 PM
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Cause, Manner, Mechanism - determined by the M.E.
198 responses, ME's had to determine the Cause, Manner & Mechanism.
Manner - Natural, Accident, Homicide, Suicide, Undetermined
Body Temperature -
The Three Mortis Brothers:
Rigor Mortis - Stiffening, body joints become stiff; 'breaking the joints' is not actually breaking the joints.
Livor Mortis - Coloring, 'lividity'
Algor Mortis - Cooling, temperature changes.
Rivor Mortis
General Rates - Average Rates
Detect - 2 to 4 hours
Complete - 6 to 12
Remains 12 - (use the handouts for these figures)
Rigor Mortis - Influencing factors: body temperature, environmental temperature, strenuous muscular activity, emotional excitement. If Body temperature is 101, stiffening will occur more quickly.
Livor Mortis/Lividity:
- blood settles with gravity after a person dies.
- Blood becomes fixed in 8-10 hours;
- prior to fixation blood will redistribute if body is moved.
- Normal color is purple.
(Area where the blood pools, will deterioate faster).
Settling of the blood (general rates):
Visible 1/2 to 4
Well developed: 3 to 4
maximum fixed: 8 to 12 hours
Influencing Factors:
- Circulatory failure - skinn livid prior to death
- Chronic anemia - acute blood loss
- Carbon monoxide poisoning
- Cyanide poisoning
- rapid cooling, snow or water
'blanching or bleaching' - area of body that is white, skin is in contact with something so the blood can not flow into this area.
Blood settles at the lowest point possible
Restrictions will cause it to settle above the area where the blood
occurs when blood cannot reach the skin; skin is in contact with an item and force is in place.
Body Location After Death (Lividity)
blanching may give valuable clues to the positioning of the deceased, remember most deaths are not instantaneous and some movement will occur.
(Body dies, sphincter, bowels relax - everything voids).
Lividity or Bruising:
Lividity will be located onliy in the skin area of the body; it may be difficult to tell if is bruising.
- Brusiing will be blocated in skin as well as the fatty tissues and the muslcles
- brusinig may have swelling or abrasions, lividity will not
coloring of bruising may vary
Medical Examiner will be able to tell
Algor Mortis - cooling of the body
General Rules
1.5 degrees per hour (at room temperature)
2.5 degrees an hour for first 6 hours
1.5 degrees for first 12 hours
1 degree per hour after 12 to 18 hours
Influencing Factors:
body temperature at time of death
Body size (fat - slower, child faster
clothing or cover
environmental factors (temperature wind humidity
immersion in water (10 x faster than air)
Dry areas, mummification, skin is turning to leather. hot dry areas; attics.
Stomach starts turning green, bacteria, enzymes, will begin start eating itself.
Marbling (veins start showing the blood vessels in the skin), skin starts to slip.
Gases in the intestines and stomach, forces out through orificies, mouth and nose, rectum, etc.
adipocere - skin peels off and turns into fatty, waxy substance. Wet, high moisture areas (not very hot).
all internal organs will also adipocere.
Positional asphyxiation - get in a position that you can't move and can't breathe. Happens quite often around military bases. Drinking so much that they fall asleep in a position they can't breath.
Auto-erotic asphyxiation - hang themselves and masturbate, pull the ripcord that releases the oxygen during the orgasm. 4 pounds of pressure on the side of your neck to cut off the oxygen to the brain. 12 pounds in front. 3 minutes brain is in trouble.
16-25 y.o. men; not too many women. women will have their husband choke them during sex.
Must be able to prove; this is not a suicide, accidental death.
Most people that do this do not do it for very long; in order to get the same effect, have to go farther.
You will find the mechanism or evidence of the mechanism. slip knot that should release the rope.
Stangling rope horizontal; hanging, rope will be a V shape.
Peticchia - suffocating or fighting for air, blood vessels in the eyes will pop, small ones will rupture. Can also happen in the eyelids, but usually in the white of the eye.
Blood froth in o.d's and in drownings. In drownings it is almost impossible to determine actual cause of death.
Blunt Force Injuries -
MedicoLegal - Know the difference between an Abrasion (scrapes); Contusions - bruise where blood has escaped into the tissue. Laceration - not a CUT, but a rip or tear in the skin from a blunt force instrument.
Bridging - stronger pieces of tissue, vessels etc that 'bridge the gap' in a blunt force Laceration. A Cut will go all the way to the bone smooth, tissue slices.
Black Eye - contusion in the ocular cavity.
Contusion heals from the outside in; yellow.
Defense wounds - anytime you have a cut from the fingerprints to the elbows, is a defense wounds or self-inflicted.
Train, car, etc. is blunt force (you're moving and hit the ground, blunt force). Long bone shoots straight through the feet. Tibia-fibias will snap.
Proof of intent to commit suicide or homicide.
Cut - incised (long cut)
Stab - Deeper than long
Chop - hatchet or axe, chopping at the person.
2 Different types of knives; single blade and double blades (military weapons, hunting knives).
Single blades wounds will create single blade point and Y.
Skin is attached to muscle tissue underneath. Muscles under the skin will pull the skin apart in the direction of the muscles. Stab wounds bleeding occurs inside; cut bleeding occurs outside.
Knives or screwdrivers.
Tips of the fingers usually defense wounds.
Work all as a homicide until you determine what it is; suicide is a homicide until you can prove intent to commit suicide.
Disclaimer: These are MY notes taken from classroom lectures while I'm in the classroom. While I'm perfectly happy to share my notes with my classmates and I know I take very good notes, you should still make every effort to attend the class and TAKE YOUR OWN NOTES. I will not transcribe everything the instructor says in the classroom, and I will NEVER post pre-exam reviews. My notes will not replace the value of actually attending class and taking your own class notes.I also cannot attest to their accuracy, other than they are what was provided in the lecture; you should not reference my notes as "expert opionion" by any means, and if you notice an error or omission, please do me the favor of e-mailing me with the correction and I will re-post my notes. End of Disclaimer.