Test 2 Estimating the time since death Flashcards
Importance of determining the Time of Death (TOD) (2)
- Identification of the victim
- Prosecution of perpetrator
Techniques used (3)
- Livor mortis
- Algor mortis
- Rigor mortis
Livor mortis
Color of the body and where the blood settle tells the position in which the body was disposed
- Visible 2 hours after death
- Most visible btw 8-12 hours
Algor mortis
Cooling off of the body after death
- Starts shortly following death
- Lasts 8-36 hours after death
Rigor mortis
Stiffening of the body
- Starts 2-6 hours after death
- Can last 24-84 hours after death
Forensic Taphonomy
A multi-disciplinary study of the stages through which the human body goes from being fresh to being completely skeletonized
Stages of Decomposition
- Autolysis
- Putrefaction
Autolysis
Liquid used for digestion. Digest the body/organs when death occurs
Putrefaction
- When micro-organisms normally residing in the body tissues begin to proliferate (increase rapidly) and breakdown biological components-> eat the soft tissues
- Because they are no longer fought by the body’s defense system
Elements that may accelerate/slow down the process of decomposition (6)
- Insect activity +
- Animal scavenging +
- Presence of plants +
- Environment
- Climate
- Accessibility- To all the previous-> +
Post mortem Intervals (7)
- Surface remains
- Buried/Submerged remains
- Animal scavenging
- Forensic Entomology
- Forensic Botany
- Deterioration of clothing
- Body fluids
Surface remains
Time of decomposition varies with types of climate
- Warm and moist (Tennessee) = Fastest
- Hot and dry (Arizona) = Mild
- Cold climates (Canada) = Slowest
Buried/Submerged remains
1 week on the surface = 2 weeks in the water = 8 weeks underground
(General observation needs to be more thoroughly investigated)
Animal Scavenging
-If only 20% of bones are found = a post-mortem interval of more than 6 months is indicated
-If 80% of the bones are found, a post-mortem interval of less than 6 months is indicated
(General observation needs to be more thoroughly investigated)
Forensic Entomology
- Life cycle of flies
- Succession of insects
Life cycle of flies
- Within minutes after death: Flies colonize the body and females begin laying eggs
- Between 6-40 hours: Eggs hatch into larvae/maggots and begin to feed on the body
- Between 3-10 days: Larvae migrate off of the body and bury themselves into the ground near the remains
- Between 6-18 days: Larvae emerge out of the ground as adult flies and return to the body.
-> Cycle of life repeats
Succession of insects
- <3days = only flies
- Between 3-13 days: Mostly flies and some beetles
- Between 13-25 days: Flies and Beetles relatively to an equal
- > 25 days = Mostly only beetles
*Insect activity may be affected by the climate and environment
Forensic Botany
Amount of plant growth beneath a surface body:
- None = < 1yr
- More compared to surroundings = > 1yr
Growth rate of vegetation:
- Ex: 1 ring in a tree= 1 yr of life-> if a tree went through a body and it has 5 rings = body is at least 6 yrs old
Deterioration of clothing
- Organic material deteriorates = <1yr
- Acrylic material is a little deteriorated = after 2 yrs
- Polyester material is a little deteriorated = after 4 yrs
Body Fluids
Body fluids at different stages of decomposition have different chemical make-up
-> Take a sample of the soil beneath the body to analyze the body fluids
