Final CSI exam V2

what is bloostain pattern analysis?

the analysis of the location, shape, size, and distribution of bloodstains

What can bloodstain pattern analysis be used to determine?

recreate actions that caused the bloodshed such as:

-# of blows

-origin of blood droplets

-direction of impact

-distance from origin

-type of impact

what is the target surface?

the surface that blood is deposited on (weapon, victim, assailant, crime scene)

What is surface tension?

cohesive forces exerted upon the surface molecules which pull towards the interior of the liquid. causes spherical shape as blood droplet falls

What is the diameter of a bloodstain the product of?

distance fallen

What is terminal velocity?

the max speed a free-falling droplet can accelerate in air

what will textured surfaces cause?

surface tension will rupture causing spines along the edges of the stain and satellite spatters

What is the impact angle?

blood that strikes a surface less than 90 degree will create eliptical bloodstains

How is directionality determined?

tail will point in direction of travel and away from area of origin

What is the formula for determining the angle of impact?

arc sin (width/length). measured in mm and doesn’t include the tail

What are the types of bloodstains?

Passive

Transfer

Void

Projected

What are passive bloodstains?

bloodstains caused from gravity

-drip (blood dripping into blood)

-pool (an accumulation of liquid blood on a surface)

What are transfer bloodstains?

contact between a blood-bearing surface and another surface with NO MOTION

-swipe (blood-bearing surface onto unstained surface)

-wipe (object moving through preexisting bloodstain)

What are void bloodstains?

absence of blood in an othewise continuous bloodstain

what are projected bloodstains?

ejection of blood under pressure/force

-cast off (released due to object in motion)

-impact (object striking blood)

-expiration (blood forced by airflow out of nose, mouth, or wound)

-arterial (blood exiting under pressure from artery)

What are the steps of the string method?

1. done after documentation but before blood evidence collection

2. pick stains with good directionality

3. determine angle of impact

4. draw line through tail in opposite direction

5. determine 2D area of convergence.

6. use stick/ruler to extend area of convergence into 3D space

7. tape string to base of blood drop and extend toward ruler at angle of impact

8. string intersection is area of origin

What is needed for accurate trajectory analysis?

2 bullet defects

What can be determined from bullet trajectory analysis?

-shooter’s location

-bullets likely location

-eliminate shooters position

what are the zones of possibility and what do they mean?

Probable (area of greatest possibility)

Possible (possible locations, would be awkward)

Impossible (not possible)

What can affect the shape of bullet holes?

-angle of impact

damaged or tumbling bullets

T/F, ricochetes do not penetrate surfaces completely

True

How do entry and exit defects appear?

Entry: regular margins

Exit: irregular margins

What is contained in a trajectory kit? (both string and laser kits)

-trajectory rods

-spacer cones

-o-rings

-strings

-lasers

-photographic fog

What are the steps for trajectory analysis?

1. determine entry vs exit holes

2. conduct vertical measurements from floor

3. conduct horizontal measurements from edge

4. record width and length of bullet hole (entry only)

5. repeat for exit holes

6. place rod with cone and o-ring in entry hole

7. measure vertical angle (up or down)

8. measure horizontal angle (left or right)

Can FARO be used for bullet trajectory analysis?

Yes, just need calibrated trajectory spheres

What are wall scopes used for?

finding and recovering bullet/bullet fragments from behind walls

What are burial indicators?

-disturbed vegetation

-soil compaction

-disturbed soil

-new vegetation

What are some factors that affect burial indicators?

-time since buried

-ground moisture

-terrain

What are some tools used in searching?

cadaver dogs

GPR (only on flat non wooded areas)

metal detectors

drones

What are associated items?

items that can give professional clues about cause and manner of death

What is the sequence of excavation?

1. search

2. grid

3. excavation

4. removal of remains

What happens during the search part of excavation?

-boundaries determined

-methods and tools determined

-search and mark/flag items

-identify margins of recovery area

What happens during the grid part of excavation?

-grid formed using stokes around perimeter and strings tied to make a grid

-provides horizontal plane of measurements

-quadrants allow for documentation

What happens during the excavation part of excavation?

-removal of ground covering layer by layer. scraping not digging

-collected in bucket and sifted

-dig around remains, leaving them elavated

-items/bones documented per level

-collect soil and insect samples

What happens during the removal part of excavation?

-remains removed and placed on bodybag

-search soil beneath body

-use metal detector

What are some things to note for surface recovery of remains?

-search animals burrows and trees

-recovery area may be larger in remains are scattered

-grid may not be necessary

What is forensic entomology?

the study of insects and related arthropods involved in legal issues

What can entomology be used to determine?

-PMI

-climate and temperature conditions after death

-loaction and movement of body

-location of antemortem injuries

-submersion of body in water

-presence of drugs in body

What happens day 1 of the blotfly life cycle?

adult fly lays eggs

What happens day 2 of blotfly life cycle?

eggs hatch and larvae emerge

What happens day 3-7 of blotfly life cycle?

develop 2 and 3 instars

What happens day 8-9 of blotfly life cycle?

prepupation larva forms hard cacoon like shell and begins developing features

When does an adult fly usually emerge once eggs layed?

2 weeks

What inhabits a body when in the fresh stage? (1-2 days)

Autolysis is occuring

-adult blowflies

-flesh flies

-yellow jackets

What inhabits a body when in the bloated stage? (2-6 days)

putrafication is occuring

-blowflies and other flies

-some beetles

-yellow jackets

What inhabits a body when in the decay stage? (5-11 days)

abdominal cavity penetrated and biomass decreases

-some flies

-some beetles

-cockroaches

What inhabits a body when in the post-decay stage? (10-24 days)

Bones hair and cartilage

-beetles

-fruit flies

-gnats

-some other flies

What inhabits a body when in the dry stage? (24+ days)

skeletal stage

-some beetles

-some ants

-some flies

What are the collection steps for entomological evidence?

1. obervations of scene, body, and insect activity

2. weather data

3. collection of specimens from body

4. collection of specimens/soil from surrounding areas

5. collection of specimens/soil from under body

6. collection of specimens during autopsy

7. ship specimens to forensic entomologist

How are adult flies collected?

-50 specimens collected

-use net to catch (sweeping method) and put in killing jar with 80% ethyl vial

-preserved only

How are adult beetles collected?

-10-15 specimens collected

-preserved in 80% ethyl vial

-preserved only

How are eggs collected?

-live only

-50 specimens

-moist paper towl with air circulation

How are fly larva collected?

-live and preserved samples

-50-60 specimens collected

-for live: beef liver and moist paper towel with air circulation

-for preserved: boil 30 sec and place in 80% ethyl vial

-collect from every location on body

How are beetle larva collected?

-10-20 specimens collected

-live and preserved

-same as fly larva

-collect from every location on body

how are fly pupae collected?

-50-60 specimens collected

-every location on body

-live and preserved

-no food

-no boiling