Forensic
Suitable for Courts of Law or for Public Discussion and Debate
Forensic Science
The application of science to criminal and civil laws through a justice system
Inferior Light for an Infrared Microscope
Used for Transmittance Measurement
Superior Light for an Infrared Microscope
Used for Reflectance Measurement
Paul Kirk
Father of American Forensic Science
What is the Challenge posed by Paul Kirk's Words?
Find; Study, Understand, Interpret significance; and properly report the evidence
How did Daubert v Merrill change Federal Rules of Evidence?
The trial judge must ensure that any and all scientific testimony or evidence admitted is not only relevant but reliable.
Reliability
Well published Methods, established guidelines; analysis performed well; proficiency testing; Accreditation and Certification
Accrediting Bodies?
ASCLD Lab
Certification through?
American Board of Criminalistics
Processing a Crime Scene
OBSERVE; SECURE; DOCUMENT
Crime Scene Reconstruction Input needed by:
Law Enforcement; Medical Examiner; Criminalists; Case Manager
Individualistic Evidence
If the characteristic is specific to an individual item it will be referred to as the opposite of class evidence and will be called individual evidence. EX. fingerprints, DNA, matched parts of a broken object.
Class Evidence
Class evidence is referred to when associated with a group of class characteristics. EX. fibers, automotive paints, adhesive tapes, photocopy toners.
Trace Evidence
Created when objects come into contact with one another. In relation to forensics, it is a very small piece of evidence left at a crime scene that may be used to identify or link a suspect and/or victim to a crime scene.
Solid Trace Evidence
Can be Macroscopic (glass, soil, hairs, fibers) or Microscopic (gunshot & explosive residues) particulates
Transfer Mechanisms
Loose fibers on surface; Fibers loosened from friction; fragmented by pressure
Number of Fibers transferred ___________________as pressure __________________.
reaches a plateau; increases
In ____________ fabrics, more of the minor constituent are transferred.
blended
Telogen Hair
A resting phase of the follicle in the cycle of hair growth, following the catogen. The hair has become a club hair and does not grow further. MOST COMMONLY TRANSFERRED
Catogen
Signals the end of the active growth of a hair. It is between the growth and resting cycle of the hair follicle.
Primary Transfer
transfer of DNA, fibers, etc. from an individual to an item first hand; or a substrate being handled and shedding cells or fibers directly. A to B
Secondary Transfer
There is no direct contact between the person and the object. It is instead transferred through an intermediary, such as another person or object. Secondary transfer theory would allow person A's DNA to be transferred first to person B's hand and second t
Persistence of Evidence
is how long the evidence stays where it was transferred. Whatever the number of fibers transferred, and almost irrespective of the nature of the recipient surface, there is an initial rapid loss of fibers. This can be as high as 80% in the first few (4) h
Factors affecting persistence
Environmental exposure; Attempts to clean surface
Longer fibers are lost_________ bc they are heavier.
faster
Redistribution of Hair and Fibers
Redistribution of material on a garment due to normal wear or laundering
Searching and Hand Tweezing
Collection of trace evidence using powerful light source and tweezers
Scraping
Collection of evidence by scraping evidence over clean sheet of paper in clean, draftless room; must be done in lab
Taping
Collection of evidence using specially designed low adhesive tape
Lifting
Collection of evidence using adhesive lifters other than tape such as lint rollers, posit-it notes
Tapings or Liftings examined under a ___________.
stereomicroscope
Stereomicroscope
a binocular microscope that gives a relatively low-power stereoscopic view of the subject.
Vacuuming
Collection of evidence using a special filtration attachment over a vacuum cleaner
Fiber Mapping
Procedure developed in 1980's; lifting or taping procedure where a series of numbered lifts are applied to surface being processed
Factors affecting number of Fibers transferred?
Surface area of contact; number of contacts; force or pressure of contact; nature of the recipient garment; fragmentation of fiber
Differential Shedding
(repeated concept) In blended fabrics, the number of fibers transferred of the different types is not proportional to the state fiber composition of the garment; Most fibers will come from the minor component bc it is less compact
Factors promoting loss of hairs and fibers from fabrics:
Continued wear; overgarments, transferred fibers situated in a place more prone to contact; low original contact pressure
A ____________ number of fibers transferred does not automatically indicate a ______________ transfer. And a ______ number; _____________ transfer.
large, primary; small, secondary