Final CSI Exam

What is the definition of BPA?

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

What is the purpose of BPA?

To reconstruct actions that caused bloodshed. Provides information on what could have and could not have happened.

Where might an investigator find blood evidence?

-victim

-crime scene

-weapon

-assailant

What is the target surface?

a surface onto which blood has been deposited

What does SWGSTAIN stand for

Scientific Working Group on Bloodstain Pattern Analysis

What kinds of information can BPA provide?

Origin of blood drops

Distance of origin to impact

Direction and type of impact

Number of blows/stabs/shots

Position of victim/assailant at time of bloodshed

Why is it important to measure the diameter of a blood droplet?

Because the diameter is a product of the distance fallen. Larger diameters are a result of increased distance fallen

When are maximum diameters acheived?

When the distance fallen from the blood source allows for the blood droplet to meet it’s terminal velocity

What happens when blood strikes a textured surface?

surface tension will rupture and spines are created along the edges of the stain.

What are satellite stains?

smaller bloodstains originating from the parent stain as a result of the blood impacting a surface

How can you determine the directionality of a blood stain?

the tail will point in the direction of travel

How is the angle of impact calculate?

Angle of impact = arc sin (width/length)

What are the types of blood stains and provide example

Passive

transfer

projected or impacted

What are passive bloodstains?

drip stain or pooling of blood. bloodstain resulting due to gravity

What are transfer bloodstains?

Contact: results from contact between blood-bearing surface and another surface. contact with no motion

Swipe: results from contact between blood-bearing surface and unstained surface

Wipe: an altered bloodstain resulting from object moving through preexisting bloodstain

What are projected bloodstains?

bloodstain as a result of ejection of blood under pressure/force.

• Impact spatter is object striking blood. cast off is drops released due to object in motion

• cast off is drops released due to object in motion

• expiration is pattern formed from blood forced by airflow out of mouth, nose, or wound.

• arterial gushing is stains formed from blood exiting body due to breached artery

What are voids?

absence of blood in an otherwise continuous bloodstain and bloodstain pattern

When is the stringing method implemented at a crime scene?

after extensive documentation/note taking/photos

before blood sampling

What is the area of convergence?

area containing intersections by line drawn through the long axes of blood stains that indicate the location of the blood source in two dimensions

What is the area of origin

3-D location from where spatter originated

What principles does bullet trajectory use?

physics and mathematics

What is required for accurate reconstruction of bullet trajectory?

two bullet defects such as bullet holes of impact sites. examples are two sided wall, door into a wall, window into a door/wall/victim

why is bullet trajectory determination important?

-determine a bullet path

-determine/eliminate shooters position

-determine bullets likely location

What are the zones of possibility?

zone 1: probable

zone 2: possible

zone 3: impossible

what type of bullet defect does not penetrate a surface all the way?

ricochetes

What is the difference that can be observed between entrance and exit defects?

entry: regular margins

exit: irregular margins with surface material pushed out

What materials are included in trajectory kits?

-trajectory rods

-spacer cones (holds rod centered) and o-rings (prevent rod from slipping through cone)

-protractor and angle finder

-string (short distances) and/or lasers (long distances)

-photographic fog (used to view and photograph laser path)

what measurements are taken for entry holes?

vertical distance from floor

horizontal distance from door/wall edge

width and length of hole

what measurements are taken for exit holes?

vertical distance from floor

horizontal distance from wall/door edge (be sure same edge as entry)

width and length of hole

What angles must be determined for bullet trajectory analysis?

vertical angle (can use angle finder for this) (side view)

horizontal angle (protractor only) (birds eye view)

can FARO be used for trajectory bullet analysis?

yes, but need to use calibrated trajectory spheres

What is a wall scope

used to retrieve bullets/bullet fragments behind walls

what is forensic pathology

study of sudden, unexpected, suspicious, or unnatural deaths.

what is forensic anthropology?

identify human skeletal remains

works with forensic pathologist/odontologist

cause and manner of death

what is forensic taphonomy?

decomposition stages

insect activity

modification by water/geology/botany

what are burial indicators?

disturbed vegetation

soil compaction

new vegetation

soil disturbance

What are some factors that affect burial indicators?

time

ground moisture

terrain

what are tools used in searching

infrared/thermal photography (drones)

metal detectors

cadaver dogs

probe

GPR

what is the search vs. recovery area

search: large area searched when investigators do not know the location of remains

recovery: area containing remains

what is the sequence of excavation of a buried body?

1. Search (determine scene boundaries, search method and tools, mark/flag items, identify margins of grave or recovery area)

2. Grid (grid created from stakes and string for horizontal measurements)

3. Excavation (using trowels to scrape layers 10cm at a time of soil. collected in bucket with grid quadrant and sifted. remains are dug around, using brushes)

4. Removal of remains (after all items documented, lay out remains on bodybag and search soil beneath)

What is forensic entomology?

study of insects and arthropods involved in legal issues

what can entomology be used for?

-PMI estimation

-climate and temperature conditions at death

-location and movement of body

-presence of drugs in body

what bugs inhabit a body at 1-2 days (fresh)?

adult blowflies, flesh flies, yellow jackets

what bugs inhabit a body at 2-6 days (bloated)?

-blowflies and other flies, beetles, yellow jackets

What bugs inhabit a body at 5-11 days (decay)?

some flies, beetles, cockroaches

what bugs inhabit a body at 10-24 days (post-decay)?

beetles, fruit flies, gnats and some other flies

What bugs inhabit a body at 24+ days (dry stage)?

some beetles, ants, and flies

what are the collection steps for entomological evidence?

1. observations of scene and body, and insect activity (habitat type, location, etc.)

2. weather data

3. collection of specimens from body

4. collection of specimens/soil from surroundings

5. collections of specimens/soil from under body

6. collection of specimens from autopsy