1 Flashcards
Define physical evidence
Any object that can establish that a crime has been committed or can link a crime and its victim to perpetrator
Circumstantial evidence
Based on inference and not personal knowledge or observation
Corroborating evidence
Evidence that differs but strengthens or confirms other evidence
Exculpatory evidence
Tends to establish the innocence of the defendant
What type of questions are addressed by examiners in the following forensic science disciplines?
-forensic biology
What is the nature of the biological fluid? Does the evidence sample have sufficient DNA to compare a known sample?
What type of questions are addressed by examiners in the following forensic science disciplines?
-forensic chemistry/toxicology
What is the substance? Is there a foreign substance present?
What type of questions are addressed by examiners in the following forensic science disciplines?
-trace evidence
Is this a hair? Is it human? What part of the body did it come from?
What type of questions are addressed by examiners in the following forensic science disciplines?
-fingerprint analyst
did the fingerprint recovered from the crime scene have the same pattern and features as one of the suspects fingerprints?
What type of questions are addressed by examiners in the following forensic science disciplines?
-firearms and toolmarks examination
what type of weapon fired the bullet? did this specific weapon fire the bullet? And what was the distance from the firearm to the victim?
What type of questions are addressed by examiners in the following forensic science disciplines?
-impression evidence
Did this shoe create the shoe impression recovered from the crime scene? What type(manufacturer, brand, size) of shoe made the shoe impression?
How is digital evidence collected and processed?
Search and analyze process
Define class characteristics
Are not unique to an object but allow an item to be included or excluded as belonging to another group
Individual characteristics
Unique characteristics that allow an item to be attributed to a specific item or person; exist in both the known and questioned samples
Comparisons are done using what type of characteristics? What conclusions can be made using comparisons?
Class characteristics; an inclusions or exclusions
Identifications require what type of characteristics
Individual, Unique characteristics that allow an item to be attributed to a specific item or person; exist in both known or questioned samples, Fingerprint features and DNA
Class or individual?
Caucasian human head hair
Class
Class or individual?
9mm bullet with a right twist
Class
Class or individual?
Microscopic striations on bullet
Individual
Class or individual?
DNA profile
Individual
Know the following databases: What do they stand for? What info is contained in them? How are they used in forensic investigations?
PDQ
Print data query, automotive paint database maintained by the royal canadian mounted police USA, world vehicles, allows an examiner to determine the make/model/year of a vehicle from a single paint chip left at a crime scene
Know the following databases: What do they stand for? What info is contained in them? How are they used in forensic investigations?
CODIS
Combined DNA Index System, missing persons
Know the following databases: What do they stand for? What info is contained in them? How are they used in forensic investigations?
NGI
Next generation identification system, contains a fingerprint and palm print database improved accuracy, faster response time , increased frequency of identification
Know the following databases: What do they stand for? What info is contained in them? How are they used in forensic investigations?
Automotive carpet database
Micro spectrophotometer(fiber color), FTIR(fiber chemical composition
Know the following databases: What do they stand for? What info is contained in them? How are they used in forensic investigations?
Footwear database
Enables determination of manufacturer of shoes from prints or impressions left at a crime scene
Know the following databases: What do they stand for? What info is contained in them? How are they used in forensic investigations?
EXPeRT
Product information (open source), technical and formulation information(proprietary), high quality photographs of products
Know the following databases: What do they stand for? What info is contained in them? How are they used in forensic investigations?
NIBIN
National Integrated Ballistics Information Network, Firearms
What types of materials are considered trace evidence?
Fibers, hairs,soil, glass,paint chips
Locards principle of exchange is the foundation of trace evidence. What does locards principle of exchange state?
Whenever two people or objects come into physical contact an exchange of materials take place
What is primary transfer?
Direct transfer- head hair falls from your head onto a chair
What is secondary transfer?
Indirect transfer- The next person who sits in chair pick up the head hair. The two individuals never had direct contact
What two methods are used to collect trace evidence?
Vacuum and scraping technique
What types of info can you get from the microscopic analysis of hair?
Animal vs human, racial characteristics, body area, damage /disease, artificial treatment, forcibly removed or naturally shed
What are the three main components of hair?
Cuticle, medulla, cortex
How do you determine if a hair is an animal hair or a human hair using microscopic analysis?
Humans have pigment granules commonly distributed towards cuticle and animals are commonly distributed towards the medulla and scale pattern
Caucasian
shaft diameter:minimal variation, pigment granules: sparse to moderately dense w even distribution, cross sectional shape: oval/elliptical
African descent (negroid)
shaft diameter:considerable variation, pigment granules:densely distributed and arranged in prominent clumps, shaft:prominent twist and curl, cross sectional shape: flattened/elliptical
Asian descent (mongoloid)
shaft diameter: coarse and usually with little to no variation, pigment granules: densely distributed and often arranged in large patchy areas or streaks , medulla:prominent, cuticle:thick, cross sectional shape: round
How can you determine the difference between a pubic hair and a beard hair using microscopic comparison?
Hair buckled-pubic hair and triangular hair-facial hair
What is a dead man’s ring? What case did we discuss that was associated with this hair characteristic ?
Kaylee Anthony case, dead man’s ring, characteristics of hair attached to decomposing body
How can you tell if a hair has been forcibly removed?
They exhibit stretching and contain a follicular tag
What are three conclusions that can be made based on the microscopic analysis of hairs/fibers
Hairs have similar in microscopic characteristics, indicating an inconclusive (included), the microscopic features of the hairs are not alike and therefore did not come from the same person (excluded), no conclusion can be drawn from the evidence.(inconclusive )This may be due to insufficient specimen or unsuitable exemplars
What are the two categories of fiber?
Natural fibers and synthetic fibers
What type of characteristics are analyzed in the microscopic analysis of fibers?
Comparison of: color, diameter,shape, presence of scales, chemical composition
Fiber color
Microspectrophotometer
Fiber chemical composition
FTIR and Cross Polarized Light Microscope
What is a physical match?
Identification
What are the two types of glass?
Tempered flat glass-shower doors, auto windows
Non-tempered flat glass-laminated windshield, architectural windows
What class characteristics(or properties) of glass are used for comparisons?
Physical properties, optical properties, chemical properties
How do you make an identification using glass?
Fractured(Physical match)
In glass, radial fractures form on the side _______ the impact of a bullet. Concentric fractures form on the ________ side as the impact of a bullet.
Opposite, same
A bullet passing through a piece of glass will form a crater that is _____ on the exit side of the glass.
Larger
Be able to distinguish a bullet entrance hole from a bullet exit hole.
Entrance-smooth exit-rough
Be able to determine which bullet hole was formed first in glass by analyzing radial fractures
Whichever line is longer from the bullet holes is the one that was first
What class characteristics are considered in soil analysis? How is soil analysis relevant to forensic science?
Chemical properties, physical properties, microscopic
pH, soil texture, biological organisms, connect back to a crime scene or location
A comparison technique to either include or exclude the evidence sample has having originated from a crime scene location
Define criminal profiles
An educated guess concerning the behavioral characteristics of an unknown offender
Does profiling use class or individual characteristics?
Class characteristics
Are criminal profiles admissible in court?
No
In criminal profiling, the focus is on the different _____ characteristics evident in a unique crime scene, and what they suggest regarding the offender.
Behavioral
What are the three goals of criminal profiling?
1)provide investigators with possible behavioral characteristics of the unknown offender
2)suggest investigative strategy and interview strategies
3)provide investigators with an idea of the types of belongings which may be found in possession of the unknown offender
Examples of cases suitable for profiling
Serial homicides, series of rapes, child abductions, child murderers, serial arson, threat communications, workplace violence, ritualistic crimes
Examples of cases not suitable for profiling
Drive by shootings and school shooters
Criminal profiling is the _____ scientific thing you will do in forensics
Least
