Forensic Entomology test

What is PMI

Post mortem interval

Define antemortem

Before death: Antemortem

Define Perimortem

At time or near time of death

Define Postmortem

After death

Stage of Decomposition; Fresh Initial Decay

Starts at time of death

End 3 days

Inside: The heart stops, the skin gets tight and gray

all muscles relax, bladder and bowels empty,

nails do not grow,

body enzymes begin to decay.

Outside:Flies lay eggs around wounds openings, Larvae move into the body

Liver mortis, Rigor mortis, Algor mortis

Stage 2 Bloat Purification

Starts 4 days

Ends 10 days

Inside: Gases in the body make skin blistered,

The whole body bloats and swell,

Tongue may protrude 

Outside: Maggots feeding in great quantity 

Stage 3 Active Decay/ Black putrefaction

starts 10 days

Ends 20 days

Inside/ Outside: Inside: Fluids from lungs oozes out of mouth and nose, Fluids leak from eyes, ears, rectum, urinary openings. Terrible smell from various gases 

Outside: Maggots are very large on body, horrible order.

The soft tissues disappear due to autolysis, insects, etc

The body collapses on itself.

Exposed parts are black in color.

Adipocere (corpse wax) Inhibits further decay. Microbeal growth. 

Stage 4 post decay

Start 20 days

Ends 50 days

Inside/Outside: The skin, hair, and nails are so loose they can be easily pulled off corpse

Outside: Most flies are gone (Beetles feed on skin and ligaments)

Stage 5 Dry/Skeletal (Mummification)

Starts 50 days

ends 365 days

Inside: Body is dry,

all hair disappears leaving only bones

Outside: Moths feeding on hair

Where on the body do investigators take the temperature after death and why?

Temp can help see when around the time the body was losing heat.

Helping determine PMI.

Though some factors can skew data

Define Algor Mortis

Starts right after death

Ends 18-24 hrs

Cooling of the body after death.

The body temp with typically drop .75 c or 1.4  F per hour for the first 12 hours then 0.4c or 0.7F per hour after

until it reaches temp equilibrium

unless outside environment is a factor

Liver stays warmest longest

Define Livor mortis or Lividity

Stars 20min-3hrs

Ends 8-12hrs

Skin gets purple and waxy,

lips finger and toe nails fade to a pale color or turn white as blood leaves,

hands and feet turn blue,

eyes sink into skull

Bloods seeps through tissue and pools at the lowest part of the body leaving dark purple stain called lividity

Indicate if body was moved 

Rigor Mortis

Stars 2-4 hrs

Peak 6-12hrs

Ends 36hrs (1-3 days)

Rigidity of skeletal muscles,

Due to loss of ATP,

small muscles effected first

Affected by environment, sex, age

What can inhibit decomposition?  What can accelerate decomposition? 

Accelerate/Inhibit: Environmental factors (temp) Activity before death, body weight

Cold temp (inhibits) Sleep (slows) Obesity (slows)

Warm temp (accelerate) Aerobic exercise (accelerates) Thin (accelerates)

Putrefaction

The breakdown of the body by bacteria, producing gases, odor, and discoloration.

Decomposition

The overall process of the body breaking down after death, including all stages.

Autolysis

Self-digestion of cells by their own enzymes right after death

What is the layer of wax called that can sometimes form on a decomposing body?

Adipocere (corpse wax)

What is the general timeline for stomach contents moving through the body?

3hrs the food then leaves and heads down towards small intestine

6hrs after eating, food traveled half way through the small intestines and begin moving though large

With victims small intestine can help determine ate meal 8hrs before death

Draw and describe the life cycle of a fly including the times for each stage.

14-16 eggs to adult

1st- adult fly lays eggs on carcass, 

2nd- eggs hatch into larvae in 12-24hrs

3rd- Larvae continues to grow and molt as they pass through instar stages

1. 5mm long 1.8 days

2. 10mm long after 2 days

3. 14-16mm long 4-5 days 

4th- Larve (17mm) develop into pupa after burrowing in surrounding soil 

5th Adult flies emerge from pupa cases 6-8 days

What is forensic entomology?

Study of insects in crime 

What is the first insect to usually arrive at a corpse?

Blowflies

What insect comes in the second succession?

Beetles

What are the two most common orders of insects at a crime scene?

Flies (Diptera) 

Beetles (coleptera)

Where is the body farm located?

Univ. of Tennessee

Western Carolina Uni. in NC

Texas State Uni.

Sam Huston State Uni. 

What are the goals of the body farm?

To understand the process of time table of postmortem decays primarily to prove the TOD

What is an autopsy; and what do pathologists try to determine from an autopsy?

The dissection of the human body to determine the cause of death.

Pathologist try and determine cause of death, manner of death, mechanism of death

What is the difference between forensic and medical autopsies?

Forensic in violent crimes or suspensions; does not require consent 

Medical determine  disease/ effects of help requires family consent 

Define the cause

Cause: Injury, disease or combo =. gunshot , stab wound, heart attack , cancer

Define Mechanism

Mechanism: Physiological, biomedical abnormality that caused the death= coronary artery disease- heart attack, cerebral edema- head injuries, hemorrhage- stab wounds

Define Manner

Manner: Circumstances in which the cause of death arose= natural, accidental, homicide, suicide, undetermined

What are the only 5 manners of death?

1. Natural

2. Accidental

3. Homicide

4. Suicide

5. Undetermined