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Logical Reasoning
Introduction
What is Forensics?
An application of science to those criminal and
civil laws that are enforced by police agencies
in a criminal justice system.
It is the responsibility of this science to provide
timely, accurate, and through information to
all levels of decision makers in our criminal
justice system.
PERFECTION IS YOUR PRIORITY!
History
Sherlock Holmes- fictional character developed
by Sir Arthur Conan Doyle; used early forensic
detection
 Mathieu Orfilia- father of forensic toxicology
 Bertillon- developed personal identification
system (based on bodily measurements). Known
as the father of criminal identification
 Francis Galton- developed first fingerprint
classification system, but was not the first to
consider fingerprints as a means of identification
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History Cont.
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Leone Lattes- discovered blood
type could be used in
identification
Calvin Goddard- refined bullet
comparison using comparison
microscope
Albert S. Osborn- est.
fundamental principles of
document examination
Hans Gross- described the
application of science to the field
of investigation
Edmond Locard- put Gross’s
method into a laboratory; est.
exchange principle
J. Edgar Hoover- director of FBI;
est. national lab aimed at offering
forensic services to all law
enforcement
Crime Lab Services
Federal Level
FBI- maintains the largest crime laboratory in the
WORLD
DEA- Drug Enforcement Administration
-(Dept. of Justice) analysis of drugs
seized in violation of federal laws
Bureau of Alcohol, Tobacco, and Firearms
- (Dept. of Treasure) analyzing alcoholic
beverages, tax law, weapons, explosives,
and related evidence
U.S. Postal Inspection Service- investigation related to
postal services
STATE LEVEL
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Must maintain a crime laboratory to service state and
local law enforcement agencies that do not have ready
access to a lab.
LOCAL LEVEL
Provide services to county and municipal agencies
KY provides 6 crime labs
- 5 regional labs and 1 central lab
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Go to kentuckystatepolice.org
10 UNITS
1.) Physical Evidence- applies principles
and techniques of chemistry, physics and
geology for comparison and identification
of crime scene evidence
2.) Biology- bloodstains, body fluids, hairs,
fibers and botanical materials
3.) Firearms- firearms, discharged bullets,
cartridge cases, shotgun shells, and
ammunition
4.) Document Examination- handwriting
and typewriting ascertaining authenticity
and/or source
5.) Photography- examines and records
evidence, prepares exhibits for courtroom
presentations
Of those 10 Units only the first five are
“basic” services, the following are optional
and are not offered by all crime labs
6.) Toxicology- presence or absence of
drugs and poisons
7.) Latent Fingerprint- processing and
examining evidence for fingerprints
8.) Polygraph- lie detector 
9.) Voiceprint Analysis- sound
spectrograph transforms speech into
visual graphic
10.) Evidence- collection; collects and
PRESERVES physical evidence to be
processed
Fingerprint Experts- dactyloscopy
Crime Scene Photographers- id technician or
identification officer: can also be trained in
fingerprint lifting and analysis
Pathologist- determines cellular changes in
tissue, studies disease; causes, processes, dev.,
and consequences
Psychologists- develops psychological profile of
the criminal
Serologists- studies blood groups and other
bodily fluids
Odontologists- examines teeth and bite marks
Ballistics Expert- study of firearms
Chemists- chemical analysis of physical evidence
Geologists- studies soil samples
Entomologists- study of insects and
decompostion
Anthropologists- study of bones to determine
height, weight, sex, race, physical characteristics
Artists- drawing likeness based on eyewitness
description or aging a photograph
Sculptors- reconstruction with modeling
clay
Linguists- analyze written and oral
communication to identify who is
speaking, speakers intent
Engineering- concerned with failure
analysis, accident reconstruction and
causes and origin of fires and explosions
Expert Witness
A forensic scientist may also provide
expert court testimony.
 An expert witness is an individual whom
the court determines possesses knowledge
relevant to the trial that is not expected of
the average person.
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The Frye Standard
The Frye v. United States decision set guidelines
for determining the admissibility of scientific
evidence into the courtroom.
 To meet the Frye standard, the evidence in
question must be “generally accepted” by the
scientific community.
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Frye Not Absolute
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Trial judges were said to be ultimately
responsible as “gatekeepers” for the
admissibility and validity of scientific
evidence presented in their courts, as well
as all expert testimony.