Chp 4 Flashcards
Wrote about Sherlock Holmes credited with first suggesting to investigators that physical objects at a crime scene could be used to identify,exclude, & prove guilt of a suspect
Sir Arthur Conan Doyle
Objects that are undetectable with the unaided eye
Trace evidence
Pioneered many of the trace evidence procedures
Paul Kirk 1902-1970
Any object that causes an image of itself by penetrating another object or surface area
Foot print tire tracks
Impression evidence
Bloody urine and semen sweat and mucus
Biological evidence
Paper or electronic contracts wills checks and other Currency
Document evidence
Physical evidence is ability to prove beyond a reasonable doubt that a specific individual committed a specific criminal act
Identifications
At least two pieces of class evidence and at least one piece of individualized evidence equals
Identification
What individual pieces of evidence have in common
Class characteristics
Every contact leaves a trace
Locates exchange principal
A process involving an unwanted transfer of physical material to a piece of evidence
Cross-contamination
Primary purpose of comparison samples is to determine the origin of an unknown piece of evidence
Question evidence
Materials taken from a verifiable source which one compared with evidence of an unknown source shown an association between the crime scene and or the fender and victim
Standard or reference samples
Uncontaminated samples compared to contaminated.
Ex: linoleum flooring that was not burned compared to a burnt section
Control samples
Fingerprints medical emergency personnel to be eliminated from scene
Elimination samples
Written record that documents the handling of any physical evidence from the time it was collected at the crime scene
Chain of custody
Collected Identified Packaged Documented Transported Stored
Evidence collection process
ALS
Fls
Alternate light sources
Forensic light sources
One of few types of evidence that can precisely identify an individual
Fingerprints
Impressions left by raise portions of skin on the palm side of the fingerprint
Friction ridges
The specific length size and patterns of these ridges which differ among all persons
Minutiae
Class Characteristics of each fingerprint
Arches
Loops
Whorls
Appearance of friction ridges that resemble rolling hills without the presence of a defined center or core Least common and prevalent in African-American
Arches
Loops begin and end in the direction of the thumb
Radial loop
Prints that begin and end in the direction of a little finger
Ulnar loop
Most common
2nd common
Least common
Loops and are most prevalent in Caucasian
Whorls
Arches most common in African American
Well defined center or core formed by friction ridges that resemble a series of tightly wound loops
Loops
A series around friction ridges graduating from small to large with a well-defined center or core resemble the inside of an onion
Whorls
Categories of prints
Visible prints paint blood
Plastic prints gum soap
Latent prints most common
The primary role to always remember when collecting fingerprint evidence
Photograph before doing anything!
Hard and non-porous surfaces
Powder developers used Metal Tile Glass Plastic
Soft and porous surfaces
Chemical developers are used
Cloth
Paper or cardboard
Iodine fuming
Can be used on most surfaces but best on paper
Ninhydrin
Works well on paper and finished wood
Turns bluish purple color in approximately 2-3 hours
Ruvis
Reflected ultra-violet imaging system
General rule of application which do you use first
Iodine fumy use first because it does not permanently alter the print
Solution capable of developing prints on wet services, developed in gray color tones, once dried prints developed with small-particle reagent form a whitish colored print
Small particle reagent
Applied to nonporous waxy your greasy metal or glass services milk cartons or interior of latex gloves and candles, produce a dark blue/black print
Sudan black
Prints left in bloody services or by bloody fingers on clean surfaces will produce a visible dark purple impression, similar results can also be obtained with ninhydrin
Leuco crystal violet
Reacts with proteins in blood to produce a dim white flourescence on prints that contain traces of blood, reactions can be produced by agents other than blood such as ones that contain vegetable proteins or bleach products
Luminol
Produces the same affect as luminal but can work much longer without a repeat application and can be visualized well with UV or other ALS lighting
Flourescein
Enhances bloody finger prints and florescence is in the presence of UV or ALS lighting pretty
Acid fuchsin
Latent prints on the sticky side of adhesive tape labels or stamps can be recovered using this method, The process involves applying the developer usually and paste form to the adhesive service and then rinsing the service with water. Within minutes a dark image of the latent print appears.
Sticky side powder
Can be applied to the adhesive side of all types to produce a developed bluish/purple print
Crystal violet
Extremely difficult to recover latent prints from skins surfaces, using this method on the surface of the skin to identify the print and then captured by transferring to print to a chemically treated metal sheet is one method that has proven effective
Iodine fuming
This method has also been proven to recover latent prints from skin or nonliving tissues
Super glue fuming
Can be applied in an attempt to develop latent fingerprints on skin as well as other surfaces contain traces of blood leaving a dark blue/black developed print
Amido black
What is the general rule of order for chemical developing methods used
Iodine fuming
Ninhydrin
Silver nitrate
Super glue fuming
Used in wet surfaces
Small particle reagent
Used on waxy or greasy nonporous surfaces
Sudan black
Used on bloody surfaces
Leuco crystal violet
Luminol
Flurescein
Acid fuchsin
Used on sticky surfaces
Sticky-side powder
Crystal violet
Used on skin surfaces
Iodine fuming
Super glue fuming
Amido black
Can lift does prints from nearly any hard flat surface as well as irregular soft services such as carpet and fabric
Electrostatic dust print lifter
A colored or clear sheet with a low adhesive gelatin surface that adheres to dust particles or other trace materials composing foot shoe tire or other prints
Gel print lifter
Photography techniques
35 mm mounted on tripod Black and white color can be used Scale and tape measure Mount directly over evidence Minimum of 4 photos of each evidence Take picture at 45 degree angle or less For tire impression every 2ft with 20% overlap
Casting impression
1lb dental stone to 6 oz of water
Pour mixture from a height not more than 2-3 inches
Overall thickness of 3/4 inches
Cast takes roughly 20-30 longer setting for cold weather
Reveal class characteristics such as the size and shape of the two
Striation marks
What are the three specific areas of ballistics examination
Internal- explosive discharge of the cartridge within the gun
External - the bullet leaving the gun barrel and its trajectory space
Terminal- the bullet striking a surface and/or coming to a place of rest
The key to determining the specific identity of a fire arm lies in the detail examination of it’s __________ characteristic
Rifiling
Most firearms(excluding ___________) contain ___________, which is composed of raised and recessed surfaces inside the barrel known as ___________ and __________.
Shotguns
Rifling
Lands and grooves
Random Micro scopic scratches
Striation marks
A chemical agent
Accelerant
The propensity to be lost through evaporation
Volatility
Collecting blood evidence
Wet blood
Use cotton swabs
Refrigerate or freeze
Collecting blood evidence
Dry blood
Scrape with a clean knife into paper packet
Tape lift
Cut out areas
Two types of presumptive test can be applied to either wet or dry blood
1st apply a chemical known as chromogen
2nd involves fluorescent light production
Other presumptive tests with in the first
Lmg(leucomalachite green) also known as hemident turns yellow to green
Kastle-meyer(km) test phenolphthalein is used in this test and turns pink when it is blood
Leuco crystal violet also used for enhancing blood prints
Blood spatter evidence is useful to for determining two things
1) The position and location of the offender relative to the victim
2) Number of times the offender wounded the victim and method of attack
This type of splatter is usually created by natural forces of gravity and is usually evidence as blood droplets falling to the ground
Low velocity spatter
She points radiating away from the drop
Spine
Curving patterns at the drops edge
Scallops
Small droplets near the edge of the drop
Satellites
At Heights greater than ___________the size of blood droplets will remain the same regardless of how far they fall
7ft
Ones cause by blunt force trauma such as kicking punching striking or stabbing leave these type patterns behind
Medium velocity spatter
This type of spatter is typically caused by gunshot wound
High velocity spatter
Consistent with high velocity spatter
Blood is forced in the direction opposite to a bullet entering the body has a maximum travel between ________and ________feet
Backward spatter
2&4 ft
Consistent with high velocity spatter
Blood projected from wounds or bullets exit the body
Forward spatter
The approximate location within the crime scene where the bleeding injury took place
Point of origin
Point of origin for
low velocity
Medium velocity
Where the blood pools where the wounding occurs
Formed on walls, floors, and ceilings
The classification and individualization of criminal evidence relating to human teeth and bite marks
Forensic odontology
Within how many hours does the photograph of bite marks need to be done
Within 8 hrs
These are made from casting the suspects dental impressions may all be used to compare bite marks obtain from suspects and victims
Bite exemplars
These indicate the direction of impact
Waller lines or rib marks
Form in a spoke like pattern extending away from the entry/ exit pool or point of contact
Radial fracture
Form in a circular pattern around the entry /exit hole or point of contact.
Exhibit perpendicular remarks on the side of the glass
Concentric fracture
When lights are on the hot filament is flexible and generally will remain intact upon impact and bend in the direction of impact
Hot shock
Cold filaments on the other hand tend to break upon impact
Cold shock
Occurs when two painted objects strike and deposit residue on each other
Cross transfer
This device enables questioned documents examiners to employ both standard and alternate light sources so that alterations to both signatures and documents can be readily visualized and photographed
Vsc video spectral comparator
Can be used to visualize indented writing on paper
Esda-electrostatic detection apparatus
