Notes : TIME OF DEATH

Notes: TIME OF DEATH

I. Death Definition: cessation, or end, of life -irreversible stopping of blood circulation -experts cannot agree on a single definition “Necrobiome”

Cause vs. Mechanism (“Physics”) 1. Cause of death: reason someone dies • Disease, physical injury, stroke, heart attack, shot, suffocated 2. Mechanism of death: describes the specific change in the body responsible for cessation of life • Cause: shooting; Mechanism: loss of blood • Cause: heart attack; Mechanism: heart stopping to beat or pulmonary arrest

II. Time of Death Tests A. Livor Mortis: “death color” -as a body begins to decompose, blood seeps down through tissues & settles into the lower parts of the body due to . -process takes time, permanent after 8 hours B. Lividity: “bluish” -pooling of blood in the body GRAVITY!!

C. Rigor Mortis: “death stiffness” 1. Temporary 2. caused by the skeletal muscles partially contracting;muscles are unable to relax, joints become fixed in place.

3. R.M. Timeline • Starts w/in 2 hours-in head and works down • At 12 hrs, body is at most rigid state • Stay rigid for 12 hrs (from 12-24 hrs) • Stiffness gradually disappears until 48 hrs. *Stiffness disappears in same direction of onset 5. Rigor for 48 hrs depend. on temp., weight, activity 6. No rigor: dead < 2 hrs or > 48 hrs 7. If rigor only in face & neck: dead just over 2 hrs Rigor Mortis Video 2 minutes

4. Factors that affect Rate of R.M. • Recent exercise • High Temp (outside and/or body) • Convulsions • Electrocution • Hypothermia • Pneumonia • Nervous sys. diseases • Low Temp (outside or body) Speed Up Slow down

ALGOR MORTIS

“Mortis” Recap • Rigor Mortis: “death ” stiffness • Livor Mortis: “death ” color

D. Algor Mortis: “death coldness” • Describes the temperature loss in a corpse • Take temperature in liver • Gives a standard comparison

1. Factors that affect cooling a. Surrounding temp & conditions • Cooler environment  Faster cooling • Windy environment  Faster cooling • Naked  Faster cooling • Clothing  Slower cooling • Excess body fat  Slower cooling b. Time of death always expressed as range • On average, body cools at 1°F per hour

2. A.M. Timeline • Death to 12 hours: • Body cools at a rate of 0.78°C (1.4°F) per hour. • After 12 hours: • Body cools at a rate of 0.39°C (0.7°F) per hour. • Body stops cooling when it reaches the SAME TEMPERATURE as its surroundings.

3. A.M. Calculations Step 1: Identify whether body has been dead for 0-12 hrs. or more than 12 hrs. • If Temp = 37°C – 27.6°C, then dead 0-12 hrs. • If Temp is less than 27.6°C, then dead > 12 hrs. Step 2 & 3: Depends…. Ex: Determine TOD if body temp. is 32.5°C.

Digestion & Entomology

Stomach and Intestinal Contents E. Digestion timeline: • 4 to 6 hours for stomach to empty • 12 hours for food to leave the small intest. • 24 hours for poop 

Conclusions: can use to help predict timeline • If undigested food in stomach, death occurred 0 to 3 hours after last meal • Stomach empty, food in small intestine, death occurred at least 4-6 hours after last meal • Small intestine empty and wastes found in lg. intestine, death 12 or more hours after meal

F. Forensic Entomology • Def: study of insects as applied to invasion on a decomposing body • helps determine TOD • Insects invade body in specific, predictable timelines. a. 1st= Flies (many types depending on location) b. Beetles arrive in later stages of decomp (many types) c. Mites and Moths may also arrive 4. Moisture, Temperature and Location affect timelines

3rd instar larva 2nd instar larva 1st instar larva

National Geographic Body Farm Video (3:37) • http://video.nationalgeographic.com/video/science/health-human-body-sci/human-body/body-farm-sci/ Entomology • http://www.youtube.com/watch?v=Ie-_bTsxGJU&list=PL1zAhPH1F4PPE5gvqHgJ3GPeP7dmd6TaB • http://www.youtube.com/watch?v=pAlLkYSEfC4&list=PL1zAhPH1F4PPE5gvqHgJ3GPeP7dmd6TaB

Entomology (8:52) http://www.youtube.com/watch?v=Ie-_bTsxGJU

Notes : TIME OF DEATH