The Postmortem Interval Flashcards
What does decomposition include?
loss of skin, muscle, internal organs, and other body components
TRUE or FALSE: decomposition continues until there is NOTHING left
true
When is estimating time since death most accurate?
within the first 24 hours
Livor mortis
the cooling of the blood after death
Algor mortis
body temperature moves towards ambient temperature
Rigor mortis
as muscle breaks down, they release a chemical that causes them to tense up
Changes in vitreous humor
eyeball fluid (really resilient to decomposition)
Forensic taphonomy
the study of what happens to bodies from the time they are deposited to when they are found
What are the four topics of PMI?
- process of decomposition 2. schedules of decomposition 3. timetables of animal scavenging 4. methods of specialists in other fields
Autolysis
digestive fluids start digesting the body until they are all used up
Putrefaction
gut bacteria start eating other parts of the body and produce a gas that causes blotaing
How do insects impact decomposition?
flies and beetles use decomposition as an easy food source
How do scavengers impact decomposition?
dismember, damage, scatter around, and expose the body to the elements
How does plant activity impact decomposition?
roots grow towards good nutrients (ex. root etching)
How was ground water impact decomposition?
it contains sediments than can mineralize bone
How does fire impact decomposition
heat! dries out the body really fast and removes organics
How does the sun impact decomposition?
rapidy dries out exposed side
How does wind impact decomposition?
carries particles away
How does water impact decomposition? (two ways)
moving bodies of water can push it into things; adipocere (fat & water) can create a little protective layer
TRUE or FALSE: warmer weather leads to slower decomposition
FALSE
Cycles of ____ and ____ disrupt connective tissue and cause the body to break down faster.
freezing; thawing
____ humidity softens the soft tissue and increases decomposition.
high
TRUE or FALSE: Decomposition is continuous, not finite.
TRUE
What did the Anthropology Research Facility in UTK discover?
Within a year, bodies and warm and moist environments are fully skeletonized.
What did researchers in Arizona discover?
Bodies in hot and dry environments become skeletonized anywhere from nine months to three years.
What did researchers in Canada discover?
Bodies in cold climates take anywhere from two months to eight years to completely skeletonize.
Why are buried and submerged remains difficult to research?
you have to dig up the body in order to observe the effects
What did Rodrigues and Bass discover about submerged remains? (ratio)
1 week on the surface = 2 weeks underwater = 8 weeks underground
What did William Haglund discover about animal scavenging?
the longer the postmortem interval, the fewer the number of bones recovered
What is the most common insect used to estimate PMI?
the blowfly
TRUE or FALSE: adult blowflies are counted in order to estimate PMI
FALSE
When does estimation with blowflies become inaccurate?
after the appearance of pupa casings as that indicates multiple generations have passed
What is the PMI if there are only flies?
less than 3 days
What is the PMI if there are mainly flies?
3-13 days
What is the PMI if there is an equal number flies and beetles?
13-25 days
What is the PMI if there are only beetles?
25+ days
What is the independent method of forensic botany?
estimating time since death by examining the rings of plant stems and roots
What is the comparative method of forensic botany?
estimating time since death by comparing nearby plant growth to farther away plants
What are the limits of forensic botany?
can only estimate PMI for individuals who died over a year ago and only in year long chunks
