forensic science
the application of science to criminal and civil laws
Mathieu Ofila
father of forensic toxicology
Alphonse Bertillion
devised the first scientific system of personal identification in 1879
Francis Galton
conducted the first definitive study of fingerprints and their classification.
Leone Lattes
developed a procedure to determine blood type from dried bloodstains
Calvin Goddard
used a comparison microscope to determine if a particular gun fired a bullet
Albert Osborn
developed the fundamental principles of document examination
Walter McCrone
utilized microscopy and other analytical methodologies to examine evidence
Hans Gross
wrote the first treatise describing the application of scientific principles to the field of criminal investigation
Edmond Locard
incorporared Gross' principles within a workable crime laboratory
Locard's Exchange Principle
whenever two objects come into contact with one another, there is exchange of materials between them
Physical Science Unit
incorporates the principles of chemistry, physics, and geology to identify and compare physical evidence
Biology Unit
applies the knowledge of biological sciences in order to investigate blood samples, body fluids, hair, and fiber samples
Firearms Unit
investigates discharged bullets, cartridge cases, shotgun shells, and ammunition
Document Unit
provides the skills needed for handwriting analysis and other questioned-document issues
Photographic Unit
applies specialized photographic techniques for recording and examining physical evidence
Toxicology Unit
examines body fluids and organs for the presence of drugs and poisons
Evidence-Collection Unit
dispatches specially trained personnel to the crime scene to collect and preserve physical evidence
expert witness
will then express an opinion as to the significance of the findings
Frye v. United States
decision set guidelines for determining the admissibility of scientific evidence into the courtroom
Frye standard
the evidence in question must be "generally accepted" by the scientific community
Daubert
set that the Frye standard is not an absolute prerequisite to the admissibility of scientific evidence
gatekeepers
admissibility and validity of scientific evidence presented in their courts, as well as all expert testimony
Daubert Criteria
1) Whether the scientific technique or theory can be (and has been) tested.
2) Whether the technique or theory has been subject to peer review and publication.
3) The technique's potential rate of error
4) Existence and maintenance of standards controllin
Forensic Entomology
the study of insects and their relation to a criminal investigation, commonly used to estimate the time of death
Forensic Odontology
using teeth to provide information about the identification of victims when a body is left in an unrecognizable state; also investigates bite marks
Rigor mortis
the shortening of muscle tissue and the stiffening of body parts in the position at death (occurs within the first 24 hours and disappears within 36 hours)
Livor mortis
the settling of blood in areas of the body closest to the ground (begins immediately on death and continues up to 12 hours)
Algor mortis
the loss of heat by a body (a general rule, beginning about an hour after death, the body loses heat by 1 to 1-1/2 degrees Fahrenheit per hour until the body reaches the environmental temperature)
The first officer to arrive at the scene
responsible for securing the crime scene
crime-scene recording
Photography, sketches, and notes
Rough Sketch
A draft representation of all essential information and measurements at a crime scene. This sketch is drawn at the crime scene. It shows all recovered items of physical evidence, as well as other important features of the crime scene
Finished Sketch
A precise rendering of the crime scene, usually drawn to scale. This type is not normally completed at the crime scene
Ordinary mailing envelopes
should not be used as evidence containers because powders and fine particles will leak out of their corners
Chain of Custody
A list of all persons who came into possession of an item of evidence
Standard/Reference Sample
Physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence
Physical evidence
almost anything, any object tat can establish that a crime has or has not been committed or can link a crime and its victim or its perpetrator
Identification
the determination of the physical or chemical identity of a substance with as near absolute certainty as existing analytical techniques will permit
comparison analysis
subjects a suspect specimen and a standard/reference specimen to the same tests and examinations for the ultimate purpose of determining whether or not they have a common origin
Probability
the frequency of occurrence of an event
individual characteristics
Evidence that can be associated to a common source with an extremely high degree of probability
class characteristics
Evidence associated only with a group
Value of class physical evidence
its ability to provide corroboration of events with data that are, as nearly as possible, free of human error and bias
Integrated Automated Fingerprint Identification System, (IAFIS)
a national fingerprint and criminal history system maintained by the FBI
Combined DNA Index System (CODIS)
database for DNA, enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles
National Integrated Ballistics Information Network (NIBIN)
firearm analysts to acquire, digitize, and compare markings made by a firearm on bullets and cartridge casings
International Forensic Automotive Paint Data Query (PDQ)
database contains chemical and color information pertaining to original automotive paints
SICAR (shoeprint image capture and retrieval)
shoeprint database
reconstruction
The method used to support a likely sequence of events by the observation and evaluation of physical evidence, as well as statements made by those involved with the incident
Physical properties
weight, volume, color, boiling point, and melting point describe a substance without reference to any other substance
chemical property
the behavior of a substance when it reacts or combines with another substance
0�C
the freezing point of water
100�C
boiling point of water
Mass
the amount of matter an object contains independent of gravity
Weight
the force with which gravity attracts a body
light waves
travel in air at a constant velocity until they penetrate another medium, such as glass or water, at which point they are suddenly slowed, causing the rays to bend
refraction
The bending of light waves because of a change in velocity
Refractive index
the ratio of the velocity of light in a vacuum to that in the medium under examination
Amorphous solids
their atoms arranged randomly, unlike crystals
Tempered glass
stronger than normal glass due to rapid heating and cooling
Laminated glass
a layer of plastic between two pieces of ordinary glass
compare glass fragments
density and refractive index
flotation method
precise and rapid method for comparing glass densities
Crystalline solids
definite geometric forms because of the orderly arrangement of their atoms
Birefringence
the numerical difference between two refractive indices
flotation and the immersion methods
used to determine a glass fragment's density and refractive index, respectively
Becke line
a bright halo near the boarder of a particle that is immersed in a liquid of a different refractive index
radial fractures
a crack in a glass that extends outward like the spoke of a wheel from the point at which the glass was struck
concentric fractures
a crack in a glass that forms a rough circle around the point of impact
Used to determine the direction of the impact
radial and concentric fracture patterns
3R Rule
Radial cracks form a Right angle on the Reverse side of the force
Soil
can be differentiated by their gross appearance
Matter
anything that has a mass and occupies space
organic substances
contain the element carbon, commonly in combination with one or more other elements
Qualitative
the identity of the material
Quantitative
requires the determination of the percent composition of the components of a mixture
Chromatography
a means of separating and tentatively identifying the components of a mixture
Spectrophotometry
the study of the absorption of light by chemical substances
retention time
The time required for a component to emerge from a GC column
TLC
thin-layer chromatography
HPLC
high-performance liquid chromatography
electrophoresis
proteins and DNA can be separated and characterized
Wavelength
the distance between two successive crests (or one trough to the next trough)
Beer's Law
The quantity of light absorbed at any frequency is directly proportional to the concentration of the absorbing species
spectrophotometer
the instrument used to measure and record the absorption spectrum of a chemical substance
mass spectrometer
a beam of high-energy electrons collide with a material, producing positively charged ions
Basic principles of dental identification
comparison, reconstruction, superimposition
laceration
a tear in tissue, inflicted when the applied force exceeds the elastic limit of the tissue concerned
Scientific method
a process that uses strict guidelines to ensure careful and systematic collection, organization, and analysis of information
buccal swab
used to collect DNA from the inner portion of the cheek
substrate control
uncontaminated surface material close to an area where physical evidence was been deposited
Product rule
multiplying together the frequencies of independently occurring genetic markers to obtain an overall frequency of occurrence for a genetic profile
Forensic pathologist
an individual who investigates sudden, unnatural, unexplained, or violent deaths
Refraction
the bending of a light wave as it passes from one medium to another
physical state
a condition or stage in the form of mater; a solid, liquid or gas
solid
a state of matter in which the molecules are held closely together in a rigid state
liquid
a state of matter in which molecules are in contact with one another but are not rigidly held in place
gas (vapor)
a state of matter in which the attractive forces between molecules are small enough to permit them to move with complete freedom
sublimation
a physical change from the solid state directly into the gaseous state
ion
an atom or molecule bearing a positive or negative charge
PMI, post mortem interval
the time that has elapsed since death
compound
two or more elements
Henry's Law
when a volatile chemical compound is dissolved in a liquid and is brought to equilibrium with air, there is a fixed ratio between the concentration of the volatile compound in air and its concentration in the liquid, and this ratio remains constant for a
Theory of light
frequency of the lower wave is twice that of the upper wave