Forensics

Question 1

a. Rigor Mortis
b. Algor mortis
c. livor mortis

Answer 1

a. body becomes stiff over time; max b/t 24-48 hrs, and then goes away
b. body cools after death; varies dependent on outside temperature
c. no systemic circulation, so blood pools at dependent portions of the body; become fixed (fixed libor) after a few hours (you can’t determine a specific time)

Question 2

a. putrefactive
b. adipocere formation
c. mummification

Answer 2

a. most common type; lipid latent fluids accumulate in body cavities, skin changes colors and slips; biggest load of bacteria is over the cecum as they can get through the bowel wall, and infect skin over cecum
b. body found in water; epidermis is dissolved; lipid layer encases the body (fresh>salt water)
c. rarer; bodies that die in the dessert/places with little moisture, they can dry up

Question 3

what questions does a ME answer?

Answer 3

1. How did they die? (ex. hemorrhage)
2. Manner of their death? (ex. homicide)
3. Why did they die? (ex. gun shot)

Question 4

Long list of types of injuries

Answer 4

Mechanical Force
– Abrasions
– Lacerations
– Contusions
– Incise wounds
– Gunshot wounds
– Blast injury
Thermal injuries
– Burns
– Hyperthermia
• Heat cramps
• Heat exhaustion
• Heat stroke
– Hypothermia
Ionizing Radiation
Electrical injuries
– Variables
– Low intensity
– High intensity
Atmospheric pressure
– Decompression (p 128R)

Question 5

When do we get for sure death from radiation?

Answer 5

10-20SV or >50 SV

small bowel; brain

Question 6

What are the three blunt force injuries?

Answer 6

a. lacerations
b. abrasion
c. contusion

Question 7

What is the wounding formula?

Answer 7

W = E x 1/T x 1/A x K

K = modifying factors (elasticity of the striking object or the tissue being injured etc)
E = Energy transferred = 1⁄2 MV2
T = Period of energy transfer (time)
A = Area of application of force

Question 8

contusion

Answer 8

• Definition: “A contusion is a bruise and results from hemorrhage into soft tissue due to rupture of subcutaneous blood vessels by blunt force injury.”
• Note: The epidermis in a contusion is intact and hence a contusion does not bleed externally. A contusion may be seen upon the skin or within deep viscera (internal organs, such as heart, lungs, brain, etc.)

Question 9

What does the extent/severity of a contusion depend on?

Answer 9

a. Amount of force applied
b. Vascularity of tissue injured
c. Type of tissue injured: areolar (loose or thin) tissue such as the eyelids - tends to bleed more
d. Location of the tissue: tissue overlying hard bony structures is more easily bruised
e. Easy bruisability: advanced age, cirrhosis of the liver, coagulopathies, etc.

Question 10

Yellow means

Answer 10

18 hours or older bruise

Question 11

Abrasion

Answer 11

• Definition: “An abrasion is a wound in which (primarily) the epidermis is injured. It is produced by friction scraping away epidermis or crushing of the epidermis by direct pressure or a blow tangential to the surface”.
• Note: An abrasion oozes serum or blood (but does not tend to bleed profusely) and generally heals by formation of a scab

Question 12

type of abrasions

Answer 12

a. Brush (or scrape or gliding) abrasion
b. Impact abrasion:
c. Patterned abrasion: Occurs when the abrasion recapitulates the surface appearance of the instrument

Question 13

Stab wound

Answer 13

Definition: “A stab wound is a sharp force injury in which the depth of the wound track is greater than the length of the wound on the skin (deeper than longer). It is produced when an instrument with a pointed edge is thrust into the body or the body falls on the pointed edge”.

Question 14

What is most important in gun wound damage?

Answer 14

velocity > mass

low velocity: small entry, no exit
high velocity: reality small entry, big exit

Question 15

Ranges of gunshot wounds

Answer 15

• Contact range: marginal abrasion; soot/powder in depths of wound
• Intermediate range: marginal abrasion, powder tattooing/stippling around wound
• Distant range: marginal abrasion, no powder tattooing/stippling, no soot/powder in the depths of a wound

Question 16

Entry path of bullet in the skull

Answer 16

external table (compact bone) –> dipole (trabecular or spongy bone) –> internal table (compact bone)

*opp for exit wound