CSI Final

Impression evidence

Objects or materials which have retained the characteristics of other objects or materials which have been impressed against them

plaster and dental stone, gelatin, rubber casting, electrostatic

what are the four techniques for casting/lifting impression evidence

plaster and dental stone

which technique for casting/lifting does 3D impressions

gelatin and other adhesive lifters

which technique for casting/lifting does 2D impressions

rubber casting

which technique for casting/lifting does tool marks

electrostatic lifting devices (ESLD)

which technique for casting/lifting does dust prints

first responders

who often destroys footwear and tire tread impression evidence

type of shoe, make of shoe, description, approximate size, location for reconstruction purposes

what five pieces of information can be ascertained from a footwear impression

2D impression

An impression with only width and length. Often in indoor crime scenes and many times on the floor leading from the point of entry

3D impression

an impression with width, length, and depth. Found indoors in flour, sugar, dust, fire extinguisher propellant or most often found outdoors in sand, mud, clay, or snow

overall, midrange, closeup, and examination quality photographs

what photographs should be taken for impression evidence

examination quality

photograph that shows impression as it was at the crime scene with any rocks, sticks, or other debris which may be in, around, or part of the impression. Ultimately, backs up casting

professional DSLR set at highest resolution

how should the camera be for examination quality photographs

place L-shaped ruler alongside impression. If 3D, place in same plane as the bottom of impression

how do you prepare an impression for examination quality photographs

oblique

what type of lighting should be used for impressions in examination quality photographs

casting

the filling of 3D footwear or tire tread impression with a material that will take on and retain the characteristics left in that impression

casting; photography

______ backs up ______ and vice versa

good viscosity, clean without losing evidence, easy to mix, reasonable set time, infinite shelf life

casting material requirements

mylar film

in electrostatic lifting, the impression is transferred by electrostatic charge to what

catalyst and resin

mikrosil casting has what two things mixed together

interior, terminal, and exterior ballistics

what three areas of study does trajectory analysis involve

forensic firearms examiner at crime lab

who conducts internal ballistics

internal ballistics

involves the function and operation of the weapon, association of weapon, bullets and cartridge cases, evaluation of ejection patterns and gunshot residue range determination

terminal ballistics

involves defining the path of the bullet throughout the body, the associated damage and differentiating entry from exit wounds. Also includes issues of range determinations

forensic pathologist

who conducts terminal ballistics analysis

close contact

the weapon is close enough for heat effects to occur to the skin. Stippling manifests itself around the wound

loose contact

wound made due to close proximity to the skin, small gap

near contact

wound made due to not more than five inches from the skin

intermediate range

wound made due to 5-40in from the skin. Only stippling appears, no heat or soot effects

indeterminate range

wound has no characteristics and therefore no conclusion about range can be determined

crime scene analyst sometime with help from firearms examiner

who conducts external ballistics

external ballistics

involves defining the path of a bullet through the scene by evaluating various scene aspects, such as penetrations and perforations, cartridge cases, and known positions of the victim or shooter. Ultimately, it defines possible and impossible scenarios for bullet trajectories

symmetrical circular or elliptical shape

entry bullet defects generally have...

irregular or asymmetrical shape with possible material pushed out

exit bullet defects generally have...

Ricochet/defection

when the bullet strikes a surface and deflects off at some angle without penetrating the surface completely. The bullet may indicate some degree of the angle it deflected

ability to evaluate impact angle

tumbling bullets eliminate what

equal

the diameter of any part of the bullet's cross section is _____ to any other

angle of impact

angle i is

inverse sine of width/length

formula for impact angle

trajectory rod, centering guides, angle finders, lasers

what four things are found in a trajectory kit

visually, presence of bullet remnants, lead or copper

how do you determine a defect is a bullet hole

roadmapping

what technique is good if there are multiple defects

lasers because doesn't interfere with trace

which is better rods or lasers

blood as a fluid responds to forces in a predictable manner

the theory of blood spatter analysis is

pattern diversity principle

the variations in combinations of blood volumes and forces acting on those volumes lead to recognizable classes of patterns

principle of stain shape and vector correlation

the shape of a bloodstain provides indicators as to the direction of deposition as well as the spatial origin of the blood

physically altered bloodstain principle

exposed blood will react to environmental conditions in a predictable manner

directionality

direction of a droplet moving at the time it struck the surface

point of convergence

the area where the reverse vectors of several related spatter stains converge on a surface

perfect circle

90 angle blood spot looks

spread out evenly

if a blood droplet falls on a smooth surface it will

surface tension is broken by irregular surface and microdroplets may form

if a blood droplet falls on a rough surface

area of origin

convergence + impact angle

spatter stains

patterns in which the primary stains are circular or elliptical

drip trail

a series of related in-line drops falling from an individual or object.

impact spatter

related small stains with consistent directional angles radiating from a central point. Progressive change in shape of stain further out

castoff pattern

series of related stains with linear or curvilinear orientation consistent with parallel directional angles. Caused by blood-bearing objects being swung

spurt pattern

series of related spatter in large volumes in a linear or curvilinear orientation in waveform. Large elliptical stains in Vs. Cause is artery or heart injury

blood into blood pattern

series of individual passive blood stains or a pooling of blood. Surrounded by a random distribution of small spatter and no consistent directional angles

swipe patterns

stain with a contiguous boundary on one side and any of the following: feathered boundary, striations in body of stain, accumulation of blood on other boundaries, diminished volume of blood across body of stain

wipe pattern

a preexisting volume of blood and any of the following: displaced blood from original boundary, dried outer ring of original stain, feathering, striations, diminished volume

blood flow

an accumulation of blood with regular margins and leading from one point on a surface to another

expectorate

related non-linear spatter with wide range of size that indicates presence of an airway injury or blood in an airway and either vacuoles/air bubbles, mucous, epithelial cells, or dilution of color due to saliva

blood pool

accumulation of blood without any specific shape but conforming to surface contours

serum separation

separation of the blood cells from plasma

roadmapping

what method is use for blood stain spatter analysis

true

T/F: bloodstains will NOT fluoresce under UV light

benzidine color test, phenolphthalein color test, hemastix, luminol, bluestar,

what tests are good for presumptive blood testing

luminol and blue star

which blood test s best for latent or hidden blood

microcrystalline tests- Takayama and Teichemann

what are the confirmatory tests for blood

1 in 100,000 parts

luminol and bluestar can detect bloodstains diluted to

precipitin test

what test is used to determine what species blood originated from

ABA HemaTrace

what test is the method of choice today

produce light from the stains, not color

luminol and bluestar do what to stains

penetration

made when a bullet goes in

perforation

made when a bullet goes in and out

bigger

exit wounds are generally _____ than entry wounds

side ways profile mark

tumbling often gives

pattern transfer

contact pattern of blood demonstrating demarcations, curves, or other recognizable characteristics of an object

amido black

can enhance a bloody handprint with what chemical

void pattern

missing portion of a blood stain

unstable structures, debris, black surfaces that don't reflect light well

what are three problematic conditions present at a fire scene

origin and cause

what is the primary objective in any fire scene investigation

origin

to seek the _____ is to look for the specific location where the fire began

cause

to seek the ________ is to identify the reason the fire began or at the very least eliminate reasons

true

T/F: fires often follow generally predictable behaviors

char patterns

fire pattern that is the result from direct flame involvement that may involve deep burning of wall studs or more subtle burning from heat convection on exterior surfaces. Can help determine the relative time a surface was burning when compared to similar surfaces

smoke/soot patterns

fire pattern that result from the outflow of fire products. They may involve horizontal demarcations over large areas or isolated vertical plumes. They help demonstrate the development and flow of the fire

damage patterns

fire pattern that occurs throughout the scene that may involve a single object or entire surfaces, heat and flame damage exposed surfaces, surfaces that are facing away or otherwise protected receive less damage, and this pattern indicates the flow of the fire at the scene.

low burn

Indicates areas of interest and nothing more. Fire naturally flows up and out, so any area in the scene exhibiting this term is of interest. Happens in arson and natural fires

v

fires generally burn in a direction of up and out producing an apparent _____- pattern at the fire scene. Helps determine flame flow and the point of origin at a fire scene

exterior

assessment of fire scenes always begins on the ________ of the scene, if possible include an elevated viewing

least; most

both assessment and observation are conducted from the _____ damaged area to the _______ damaged area

airtight packaging like clean paint cans & wide mouth glass jars

what is arson evidence stored in

intelligence that a body was dumped at a specific time at a specific location

landfill recoveries usually involve what prerequisite

waste cells

pockets of trash that are separate from other pockets of trash. These are how managed waste sites function and help maintain specific records of routes

compacting of trash, heat from decomposing trash, hazards in the landfill

three problems in landfill recovery

remove trash a few buckets at a time, spread trash over open area, bulldoze from search area when searched, pus to holding area

four steps of landfill search methodology

grid and datum point

what is established for scattered remains over a wide area

line search

what is the most effective search pattern for scattered remains