HOSA - Forensics

What are the charcteristics of algor mortis?

Algor mortis can be slowed or sped up due to certain conditions. Slow Down - extra body fat, hot and humid environment, body wrapped in blankets, thick clothing Speed Up - small victim, very cold environment, body laying on concrete (as opposed to a carpet)

When does rigor mortis fully set?

12-18 hours after death

When do eyes get cloudy after death if they are closed?

24 hours

When do muscles start to relax (rigor releases)?

24-48 hours after death

If the stomach is empty, but the small intestine is full, how long did someone die after their last meal?

4-6 hours

When does livor mortis become fixed?

8 hours after death

Is using digestive contents in a forensically relevant way reliable?

It is the least reliable source to determine a post-mortem interval, however it can still be used if we know when the last meal was.

What are characteristics of digested food?

Using digested food in a forensically relevant way can vary in different circumstances. Slow Down - ate tough foods for a last meal, suffered from a lot of stress, sick with an illness Speed Up - ate soft foods for a last meal, sick with an illness, chewed their food well before swallowing

What is a contusion?

a large bruise that may indicate blunt force trauma

What is a laceration?

a large, deep, and jagged wound; a tear to the skin

What is an abrasion?

a scrape on the skin, may show that a victim has been dragged

If the small intestines are empty, how long did someone die after their last meal?

at least 12 hours

If the large intestines are empty, how long did someone die after their last meal?

at least 30 hours

When does rigor mortis start?

begins 2-6 hours after death

When does livor mortis begin?

begins around 1-2 hours after death

What is the first insect at a body?

blowflies are the first. they have an incredibly large olfactory complex that allows them to smell a body. as soon as they arrive, they will be attracted to body cavities to look for a moist place to lay their eggs.

What are some forensically relevant insects?

blowflies, fleshflies, and beetles

What are signs of asphyxiation and strangulation?

bruising or marks on neck, broken blood vessels in eyes or lungs, broken hydroid bone, crushed trachea, petechiae around or in the whites of eyes

What is the life cycle stage of blowflies?

eggs —> first instar maggots —> second instar maggots —> third instar maggots (migrating maggots) —> pupa —> young adult (wrinkled wings) —> adult fly

What is important information we can gain from knife wounds?

how long and wide the knife was

When does algor mortis begin?

immediately after death

If you found traces of poison in urine and bile, when were they poisoned?

in days prior to death

If you found traces of poison in a stomach, when were they poisoned?

in the last meal before death

If you found traces of poison in hair and nails, when were they poisoned?

in weeks, months, or years prior to death

What is the formula for algor mortis?

the body loses 0.75ºC per hour for the first 12 hours and then 0.4ºC per hour until the body reaches the temperature of the environment

What is livor mortis?

the discoloration of the body after death (blood pools in areas where gravity is acting)

What is the cause of death?

the reason someone dies (ex : heart attack, stroke)

What is the mechanism of death?

the specific change in the body that brought about the cessation of life (ex : blood clot stopping blood from moving to the brain)

What is rigor mortis?

the stiffening of the body after death

What is forensic entomology?

the use of the insects and other arthropods that feed on decaying remains to aid legal investigations

What is a manner of death?

the way to categorize death (5 categories)

When do eyes get cloudy after death if they are open?

within 2-3 hours

If you found traces of poison in the eyes and blood, when were they poisoned?

within the last hours before death?

What are defensive wounds?

wounds a victim may have from fighting back (will find on hands and arms from fighting back)

What are the five manners of death?

- Homicide - Suicide - Accidental - Natural - Undetermined

What are characteristics of the fresh stage of decomposition?

- autolysis and all three mortis' set in - bladder and bowels empty due to loss of muscle control - eyes cloud over (if open) and (blow)flies arrive at the body

What are some characteristics of livor mortis?

- blood pools in areas closest to the ground (ex : if a body is laying on its back, the blood will pool in the back half of the body) - If the body has areas of blood pooling that does not match the gravitational pull, then the body was moved sometime within the first 2-8 hours before the livor mortis was set (ex : if a body sitting up also shows livor mortis on the right side, they were originally laying on their right side)

What are the five stages of death?

- fresh stage - putrefaction/bloat stage - active decay - advanced decay - dry remains

What are the characteristics of putrefaction/bloat stage?

- loss of rigor - gases cause body cavities to swell or bloat - skin easily separates from underlying tissue and may appear marbled - pervasive odor - increased insect activity and may start to see egg masses - liquefaction of body tissues

What are characteristics of the active decay stage?

- massive loss of body tissues due to insects activity - decomposition island forms around body - body cavities swell and burst due to build up of gases - intense insect activity

What are characteristics of the advanced decay stage?

- most soft tissue gone - adipocere forms at the beginning (a greasy wax) - smell dissipates

What are characteristics of the dry remains stage?

- only bones remain - skeletal structure

What are some characteristics of rigor mortis?

- small muscles will contract first (hands, feet, facial muscles) - larger muscles will contract last (large leg muscles, torso, etc) - small muscles will be the first to release - large muscles will be the last to release - physical exercise before death can cause someone to go into rigor sooner than someone who was sitting or resting

What are signs someone has died by drowning?

- water in the lungs - plant matter/sand in the lungs - water microorganisms in lungs

If there is digested food in the stomach, how long did someone die after their last meal?

0-3 hours

Rule of Thumb Post-Morten Interval

Body Warm and Limp - Dead less than 3 hours Body Warm and Stiff - Dead 3-8 hours Body Cool and Stiff - Dead 8-36 hours Body Cool and Limp - Dead more than 36 hours

How do you know when livor mortis is "set"?

If you put pressure on an area where the blood has pooled and it turns white, it is not yet set. If the color does not change, it is set.

What can change the rate of decomposition?

Slow Down : healthy individual, older people, average mass, clothed bodies, low humidity or high temperature (dry out and preserve tissues), colder temperatures, buried or underwater Speed Up - illness or advanced disease, young people, large fat or fluid deposits, unclothed bodies, humid and high temperatures, exposed to air

What is algor mortis?

cooling of the body after death until body temperature matches ambient temperature