Crime Scene Investigation Final

establish what occurred during the shooting event

Purpose of doing a shooting scene reconstruction

shell casings and bullet holes

most useful in determining the number of shots fired in shoot scene reconstruction

internal ballistics, external ballistics, terminal ballistics

trajectory analysis involves 3 areas of related ballistic study which are:

each area of study is necessary to understand the scene

longer the barrel the greater the acceleration

relationship between the length of the barrel and the acceleration of a gun (up to a point)

defining the path of a bullet through the target surface/body, the associated damage, and differentiating entry from exit wounds

terminal ballistics involves __________, __________, and ___________

velocity of the bullet

most significant factor in an increase or decrease of kinetic energy of a bullet in terminal ballistics

bullet velocity, mass

increases in _______ have greater effect on the kinetic energy than the bullet _______

close contact

pressed to the skin range deterministic

close

not more than 5 inches from the wound range deterministic

intermediate range

5-40 inches from the wound range deterministic

tattooing/stippling

unburned gunpowder is a characteristic of entrance wounds that causes _______ which are characteristic markings on the skin

triangular tears, soot, muzzle contusion (muzzle stamp), NO tattooing/stippling

tight or loose contact wound characteristics

tattooing/stippling from unburned gunpowder

characteristic of 0-5 inches of a close range GSW

does not differentiate, configuration

size ____________ entrance from exit wounds, _______ of wound does

cartridge case, primer, powder charge, bullet/projectile

cartridge components

terminus

final resting place where projectile ends up after it’s flight path (final target surface)

french fry

compressed and punched out section of foam padding creating the shape and appearance of a ___________

perforation defect

going through something

penetration defect

going into something

wider

in glass, a projectile hole is inevitably _________ at the exit side

fracture

in successive penetrations a _______ always terminates at an existing line of fracture

trajectory rods, centering guides, angle finders and protractors, lasers

components of trajectory kits

RODS and lasers

parts of trajectory kit used to reconstruct trajectory of a b*llet

direction and angle

trajectory analysis is used to determine ______________ the bullet traveled

angle

centering guides to level the rod in the defect but can also affect the ________ significantly

acute angle

angle of incidence is determined by the _________ and must use a direction (left/right, front/back)

rifled barrel

barrel of a g*n can be ________ to put spin on bullet; increases true and accurate course

inside of the barrel has lands and grooves. the barrel leaves unique markings on the bullet

lands and grooves

rifled barreling involves making _________ by forcing cutting tools through the tube

minor differences in manufacturing leads to differences in the scratches (striations) on the fired bullet

manufacturer, shape, caliber, composistion

cartridge case class evidence

breech face marks, firing pin impressions, chamber marks, extractor marks, ejector marks

cartridge case individual characteristics

side-by-side

comparison microscope compares striations __________ so markings left on a cartridge case or bullet can identify the specific firearm used

striations

tiny, unique scratches on bullet that can be specific to a single gun

class characteristics and striations

if these two things match then can say the bullet was likely fired by the suspect gun

firing pin marks

these can link a spent cartridge to a specific firearm this part is responsible for firing a bullet from a gun

NIBIN (National Integrated Ballistics Information Network)

specialized computer network in the US

contains digital images of recovered pieces of ballistic evidence

can use information from previous entries to establish connections

associate previously unrelated crimes generating investigative leads, arrests, and convictions

IBIS (integrated ballistic identification system)

uss sophisticated electronic and optical technology to digitally compare evidence stored in the database

MAY

if the suspect’s gun is loaded, ______ conduct ejection pattern tests

not a reliable method

discharged cartridge case patters are ______________

nature and appearance

by analyzing the ____________, BPA is a process to reconstruct events

less spatter results

harder and less porous the surface, the ______________ for BPA

irregular shapes with serrated edges

rough surfaces usually result in _____________________, possibly with satellite spatter in BPA

pointed end of bloodstain

the direction of travel of blood striking an object may be discerned because the _____________ always faces its direction of travel

small, circular, and/or elliptical shaped stains

spatter stains are ________

impact spatter

occurs when an object impacts a source of blood

consistent, central point

impact blood spatter patterns have related small stains with ________ directional angles and they radiate from a _________

low velocity spatter

drops with diameters of 4mm or more normally produced by an applied force of up to 5 ft/sec. Associated with minimal force

medium velocity spatter

drops with diameters from 1-4 mm with an applied force of 5 to 25 ft/sec. Usually associated with blunt force trauma

high-velocity spatter

drops with diameters of less than 1 mm from an applied force of 100 ft/sec or faster (gunshot wounds or explosions)

gunshot spatter is fine forward spatter from an exit wound and back spatter from an entrance wound

cast-off spatter

a _________ is created when a blood-covered object flings blood in an arc onto a nearby surface i.e. bloodstains on a ceiling

spurt pattern

large elliptical stains line of stains or overlapping stains oriented in Vs, arcs or serpentine patterns

arterial spray

________ spatter is caused by an injury to the heart or a main _______ and the pressure of the continuing pumping

has a spiked patter, similar to an EKG

gush/splash/projected spatter

large elliptical stains

expectorate blood patterns

an _________ is created by blood that is expelled from the mouth or nose from an internal injury

presence of an airway injury or blood in an airway (nose or mouth)

blood into blood pattern

surrounded by a random distribution of small spatter, the spatter will generally not have a consistent directional angles

satellite patterns

these patterns arise from blood droplets that leave the parent stain by some degree of force

contact/transfer patterns

a _____________ is created when an object with blood on it touches one that does not have blood on it

bloodstained object contacts a surface, and leaves a mark. The size and general shape of the object may be seen in a simple transfer

pattern transfer

demonstrating demarcations, curves or other recognizable characteristics of an object

swipes

a bloodstained object moves across a clean surface (a transfer stain in motion)

wipes

a pattern caused by an object coming into contact through lateral motion with a pre-existing bloodstain on another object

can be distinguished by the presence of skeletonization of the original bloodstain

flows

if blood _____ pattern does not appear consistent with gravity, one may surmise an object or body gas been moved

blood pool

without any specific shape, but conforming to the surface contours

it may demonstrate serum separation - collect white blood cells for DNA analysis

drop trail patterns

a _____________ is a series of drops that are separate from other patterns, formed by blood dripping off an object or injury

void patterns

created when an object blocks the deposition of blood spatter onto a target surface or object and the spatter is deposited onto the object or person instead

grid method

squares of known dimensions are set up over the entire pattern used to document bloodstain evidence

perimeter ruler method

a rectangular border of rulers is set up around each pattern and a smaller ruler next to each stain used to document bloodstain evidence

luminol

checking scenes of suspicious disappearance for indications of clean-up uses the compound ________

class characteristics

a trait or characteristic that allows the item to be compared with another group of items and included or excluded in the group

individual characteristics

a trait or characteristic that allows the item to be compared to an sole item or person

trace evidence

small materials that may be transferred during a crime that includes hairs, fibers, glass, paints, soils, gunshot residues

links suspects to crimes or locations

can rule out suspects

can support or refute alibis

Locard’s theory of exchange

theory that states every contact leaves a trace

trace elements

may establish the source of a material or at least provide additional points for comparison

hair and fibers

success for individualizing human _____ has been achieved by isolating and characterizing the DNA present in the ______

root

when forcibly removed from the head, hairs are most likely to provide DNA because they bear some translucent tissue surrounding the hair’s shaft near the _______ may be found. This is called a follicular tag

hair shaft without the ______ is less likely to contain usable DNA

mechanical fit

an individualization by fitting two or more pieces of something together i.e. hit and run

paint

one of the most common types of ____ examined in the crime laboratory involves finishes emanating from automobiles

number

most forensically significant feature of paint is _______ of color layers

soil

most can be differentiated by their gross appearance

a side-by-side visual comparison, under a microscope, of the color and texture of _____ specimens is easy to perform

contaminants or unique environmental characteristics

greater individualization of soil may be possible due to ______________

prints or marks made by an object containing a surface

type of impression evidence

shoe size, tread pattern, wear pattern, cut, gouge, damage

physical characteristics of footwear impression evidence includes

imparts INDIVIDUAL characteristics to a shoe

determine number of suspects

footwear impression evidence involves patterns which help with

impressions and prints

two forms of footwear evidence

remove the vehicle

to collect tire prints you must _________ from the scene and transport to a secure facility for processing

machining

each tool is manufactured similarly - resulting in class characteristics (size, shape, nature of the tool)

the process of ________ or the subsequent use of the tool may leave unique accidental marks

scratches, nicks, wear

presence of any minute imperfections on a tool that imparts individuality to a tool includes - as unique as fingerprints

less distinctive

two main types of bite mark impressions include antemortem which are ________. Photograph for several days

well-defined

two main types of bite mark impressions include postmortem which are _______ no bruising

definite

to the exclusion of all others (i.e. only the suspect could have made the bitemark impression)

consistent

no features present that will exclude the suspect in terms of a bite mark

possible

due to nature of injury, unable to positively confirm or exclude the suspect in terms of a bite mark

exclusionary

definitely not a bitemark made by the suspect

DNA (deoxyribonucleic acid)

building block of life, present in every cell nucleus. No two DNA samples are the same

double helix

the DNA molecule is comprised of two strands each wrapped around the other in the form of a __________

A-T and G-C

pairs of DNA

Sir Alec Jeffreys

in 1984 ___________ discovered first DNA “fingerprint”, the father of DNA fingerprinting

distinguish every individual in the world

DNA fingerprinting demonstrated that DNA profiling can

identify the individual that contributed the sample

main purpose of DNA profiling in forensic science

restriction fragment length polymorphisms (RFLP)

length differences associated with relatively long repeating DNA strands and form the basis for one of the first DNA typing procedures

Polymerase Chain reaction (PCR)

technique for replicating small quantities of DNA or broken pieces of DNA found at a crime scene, outside a living cell

amplify minute quantities of DNA many millions of times

PCR offers a distinct advantage in that it can ______________