Download Criminalistics Overview - Fall River Public Schools

Criminalistics
Overview
B.M.C. Durfee High School
Objectives
• Recognize and discuss subspecialties in the
field of forensic science
• Identify and discuss the steps criminalists take
regarding evidence when solving crimes
Introduction
• Criminalists use to be looked upon as a “jackof-all-trades”
• Criminalists now can be very specialized
• The American Academy of Forensics Sciences
identifies several subspecialties
Crime Scene Investigation
Overview Video
Crime Scene Investigation Overview
Forensic Drug Analysis
• Use analytical chemistry to ID the presence
and quantity of controlled substances
• Also investigates information about drugs,
such as the country of origin
Forensic Chemistry
• ID’s and analyzes toxic substances, fire
accelerants, gunpowder residue, explosives etc.
• Make comparisons between known and
unknown materials
• May attempt to trace unknown substances to a
specific origin
Analysis of Trace Evidence
• They examine hair, fibers, glass, soil, plants,
minerals etc.
• They use microscopes and chemical techniques
to ID evidence that is usually found in small
quantities
Firearm Examination
• Analyze firearms, discharge bullets,
cartridge cases, shotgun shells,
homemade weapons, and
ammunition components
• They try to answers questions like:
o What kind of weapon fired the
bullet?
o Did this particular weapon fire
this bullet or cartridge case?
o Is the weapon functioning
properly?
o What was the trajectory and
distance of the shot?
Latent Fingerprints
• “Latent fingerprints” are fingerprints that are
invisible to the human eye
• They process the fingerprints using techniques
such as chemicals or instrumentation to detect
fingerprints
o The evidence is sent to a forensic laboratory
o The prints are compared to known people
to try to ID the criminal
Voice Analysis
• Just as each person has different fingerprints,
each person also has unique speech patterns
o The patterns are displayed in a spectrogram
and compared to known samples
• Voice analysts also examine aircraft “black
boxes” after an incident
Forensics Serology
• They use biochemistry, serology (the study of blood
serum and body fluid). immunology, hematology, and
molecular biology to ID and individualize blood
and other body fluids
• Serologists ask questions like?
o
o
o
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Is this the stain of a body fluid?
What type of body fluid was it?
What species did the stain come from?
Does the stain have the same blood types or DNA
profile as a known sample?
o Can we reconstruct the evidence to determine
where it came from?
DNA Analysis
• Forensic biologists extract & analyze DNA from
blood, semen, bones, body tissues, hair roots,
saliva, fecal matter etc.
• They can use DNA amplification techniques
when there is only a small sample of evidence
Questioned Document
Examiner
• They look at handwriting, typewriting,
printing, photocopying, and any other
mechanical production of written material
• Also analyze ink, paper, and other components
of the document
• Document examination is a valuable tool in
white-collar crime investigations
Steps of Investigation
1. Recognize the potential physical evidence at the crime
2- Document, collect, and preserve physical evidence
3- Identify what the evidence is
4- Classify the evidence by comparing it to known
standards
5- Individualize the evidence- document that evidence is
absolutely related to a particular source
6- Evaluate the evidence by conducting lavatory test and
analysis
7- Reconstruct the chain of events in a crime by analyzing
the physical evidence and interpreting the patterns at
the crime scene
Review
• Identify the
subspecialties in
forensic science:
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Forensic Drug Analysis
Forensic Chemistry
Analysis of Trace Evidence
Firearm Examination
Voice Analysis
Forensics Serologist
Forensic biologists
Questioned Document Examiner
• Identify the steps
criminalists take
regarding evidence
when solving crimes
Review…
Recognize physical evidence at the crime
scene
Document, collect, and preserve physical
evidence
Identify what the evidence is
Classify the evidence
Individualize the evidence- document that
evidence is absolutely related to a
particular source
Evaluate the evidence by conducting
lavatory test and analysis
Reconstruct the chain of events in a crime
Learn Long
Live Long