Download ID: Drugs, glass, paint, explosives, soil and trace

A. Basic Services of a Full-Service Lab:
1. Physical Science Unit- Applies principles and technologies of chemistry,
physics and geology to identification and comparison of crime scene evidence.
ID: Drugs, glass, paint, explosives, soil and trace physical evidence
2. Biology Unit- Staffed with biologists and serologists who work in the identification and typing of dry blood stains and
other body fluids, the comparison of hairs and fibers, and the identification and comparison of botanical materials
such as wood and plants.
3. Firearms Unit- Conducts examination of firearms, discharged bullets, cartridge cases, shotgun shells, and ammunition of
all types. Garments and other objects also examined to detect firearm discharge residues and to approximate
distance from target at which weapon was fired. This unit also compares marks made by tools.
4. Document Examination Unit- Studies the handwriting and typewriting on questioned documents to determine
authenticity and/or source. Also analyze paper and ink as well as indented writings, obliterations, erasures, and
burned or charred documents.
Indented writings- Partially visible depressions appearing on a sheet of paper underneath the one on which the
visible writing appears.
5. Photography Unit- Used to examine and record physical evidence. Procedures use techniques such as infrared,
ultraviolet, and x-ray photography to make invisible information visible. Also aids in preparation of photographic
exhibits for courtroom presentation.
B. Optional Services for Full-Service Lab:
1. Toxicology Unit- Body fluids and organs are examined by toxicology to determine the presence or absence of drugs and
poisons. Much of this work is shared or completely given to a separate lab under the direction of the Coroner’s
office.
Tox. field instruments include the toxilizer, which is used to determine the alcoholic consumption of a person.
Also has responsibility for training operators and maintaining and servicing their instruments.
2. Latent Fingerprint Unit- Responsible for processing and examining evidence for latent fingerprints. I.e. process a glass
for fingerprints.
3. Polygraph Unit- The polygraph is a tool of the criminal investigator, rather than the forensic scientist. In the early years
of the polygraph, police agencies incorporated this unit into the lab. Its functions are, and have always been,
handled by people trained in techniques of criminal investigation.
4. Voiceprint Analysis Unit- Work in cases involving telephoned threats or tape-recorded messages. The unit analyzes and
attempts to tie the voice to a particular suspect using a sound spectrograph.
Sound Spectrograph- instrument that transforms speech into a visual graphic display called a voiceprint.
***Sound patterns produced in speech are unique to the individual. A visual voiceprint can display this uniqueness.
5. Evidence-Collection Unit- Dispatches specially trained personnel (civilian and/ or police) to the crime scene to collect
and preserve physical evidence to be processed at the lab. This unit is slowly gaining recognition in the U.S.
C. Other Forensic Services:
1.
Forensic Pathology:
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Involves the investigation of sudden, unnatural, unexplained or violent deaths. Forensic Pathologists serve as coroners or medical
examiners.
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They must answer the following questions:
1.
2.
3.
4.
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Who is the victim?
What injuries are present?
When did the injuries occur?
How and why were the injuries produced?
The primary role of the medical examiner is to determine the cause of death through observation or autopsy.
Five Categories of Classification of Death:
1.
2.
3.
4.
5.
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Natural
Homicide
Suicide
Accident
Undetermined
Classification of death is based on circumstances surrounding the incident.
Determining the Time of Death:
M.E.’s can estimate the time of death by evaluating the stage of decomposition in which the victim was found.
Stages of Decomposition:
A.
Rigor Mortis- Immediately following death the muscles relax and then become rigid without shortening of the muscles. It
manifests within 24 hrs. and disappears within 36 hrs.
B.
Livor Mortis- Occurring in the early stages of decomposition when the heart stops pumping, the blood begins to settle in
the parts of the body closest to the ground.
The skin appears dark blue or purple in color in these areas. Onset of this condition begins immediately and continues for
up to 12 hrs. after death.
The skin will NOT appear discolored in areas where the body is restricted by either clothing or an object.
Obtaining this info can be useful in determining if the victim’s position was changed after death occurred.
C.
Algor Mortis- The process in which the body temperature continually cools after death until it reaches the ambient or
room temperature.
The rate of heat loss is influenced by; body size, location of body, clothing, and weather conditions. Because of such
factors, this method can only estimate the approximate time period since death.
D.
Vitreous Humor Potassium Levels- Another way to estimate T.O.D. is to measure potassium levels in ocular fluid.
After death, cells within the inner surface of the eyeball release potassium into the ocular fluid.
E.
Other Factors used in Estimating T.O.D.Stomach contents- amount of food in stomach can help estimate
when a person’s last meal was eaten and where.
Autopsy- M.E.’s must perform autopsies if a death is deemed suspicious or unexplained.
2. Forensic Anthropology:
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Concerned primarily with the ID and examination of human skeletal remains.
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Skeletal bones are durable and resist rapid decomposition.
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Examination of skeletal remains can reveal origin, sex, approx. age, race, and skeletal injury.
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Ex. Female pelvis VS. Male pelvis- larger due to childbearing
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Ex. Sex differences in the adult long bones are a matter of size.
than typical female
long bones.
capabilities.
Typical male bones are longer and larger
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Forensic anthropologists may also assist in creating facial reconstruction to aid in the ID of skeletal remains.
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Forensic anthropologists are also helpful during the ID of victims of a mass disaster, such as a plane crash.
3.
Forensic Entomology:
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Forensic entomology is the study of insects and their relation to a criminal investigation. This practice is commonly used to
estimate the time of death when the circumstances surrounding the crime are unknown.
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After decomposition begins, insects such as carrion flies are the first to infest the body. Their eggs are laid within the human
remains and ultimately hatch into maggots.
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Maggots are responsible for the consumption of human organs and tissues. The forensic entomologist can identify specific
insects present in the body and approximately how long a body has been left exposed by examining the stage of development
of the fly larvae.
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The time required for stage development is affected by environmental influences such as climate and weather conditions.
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4.
Ex. Cold temps. will hinder the progress of fly eggs into adult flies.
Forensic Psychiatry:
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A specialized area in which the relationship between human behavior and legal proceedings is examined.
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Forensic Psychiatrists are retained for both civil and criminal litigation.
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5.
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Civil cases: F. P.’s normally determine whether people are competent to make decisions about preparing wills, settling
property, or refusing medical treatment.
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Criminal cases: They evaluate behavioral disorders and determine whether people are competent to stand trial.
F. P.’s also examine behavioral patterns of criminals as an aid in developing a suspect’s behavioral profile.
Forensic Odontology:
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Provide info for the ID of victims when the body is left in an unrecognizable state.
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Teeth are composed of enamel, the hardest substance within the body. Because of its resilience, teeth will out-last tissues
and organs as decomposition begins.
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The characteristics of teeth, their alignment, and overall structure of the mouth provide individual evidence for identifying a
specific person. With the use of dental records such as X-rays, dental casts, or pictures of a person’s smile, a comparison can
be made between a set of dental remains and a suspected victim.
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Forensic odontologists also do bite mark analysis. They analyze the marks left on a victim and the teeth structure of the
suspect in order to make a comparison.