ifting latent fingerprints from narcotics packaging prior to
analysis by the Narcotics Analysis Unit.
The fastest growing and
potentially most useful forensic tool in the Forensic Laboratory is
the science of DNA analysis. Conventional typing of genetic markers
such as the ABO blood group system, and of the polymorphic blood
enzyme sub-systems such as PGM, have given way completely to the
typing of Deoxyribonucleic Acid (DNA). The only exceptions are the
identification of the semen-specific protein P30 in semen stains, and
species identification of bloodstains.
The conventional biological fluid
typing systems are generally limited to the typing of blood, saliva,
and semen. DNA analysis is much more versatile and can be performed on
virtually any tissue containing nuclear DNA material: blood, saliva,
muscle tissue, semen, vaginal secretions, bone, skin tissue, feces,
urine, and hair. In addition, the DNA methods currently in use in the
Forensic Laboratory utilize a DNA amplification technique, making them
extremely sensitive. DNA analysis, unlike the old enzyme systems,
requires only small amounts of evidence material.
Because DNA analysis is so
sensitive and complex, it requires extraordinary skill and training on
the part of the Identification Technician who collects the biological
material at the scene, as well as the Criminalist who analyzes it in
the laboratory. The Identification Technicians in the Crime Scene
Unit are specifically trained in the collection techniques. The two
Criminalists who specialize in DNA analysis hold Masters of Science
degrees, in addition to the Bachelor of Science degree normally
required of a Criminalist.
A new DNA analysis system, called
STR (for Short Tandem Repeat), is currently undergoing validation and
is scheduled to go on line in 2003. This will effectively allow the
conclusive identification of individual persons; the chance of finding
two persons with the same DNA type in the STR system is approximately
one in a trillion, or the equivalent of about one million planet earth
populations.
The development of the ability to
conclusively identify a person by their DNA is comparable to the
quantum leap made in the science of identification in the early 1900s,
when the science of fingerprints supplanted the Bertillon measurement
system. In fact, DNA typing is potentially even more useful than
fingerprints; the estimated probability of any two persons having the
same fingerprint pattern is 1 in 67 billion, or the equivalent of only
about ten earth populations.
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The analysis of firearms related
evidence is one of the mainstays of the Forensic Laboratory, with two
Criminalists specializing in this unique area of expertise. In
addition to conventional firearms comparison examinations, the
Laboratory administers one of the five National Integrated Ballistic
Information Network (NIBIN) sites in the Central Valley, and provides
research and testing services of duty ammunition for the Sheriff’s
Office.
Toolmark and Firearms
Comparison Examination
Conventional firearms evidence
comparison and examination consists of the familiar identification of
bullets and cartridge casings collected at crime scenes by
Identification Technicians in the Crime Scene Unit. This type of
identification is as powerful in identifying a firearm as latent
fingerprints are in identifying a person.
Firearms comparison is actually a
specialized area of the science of toolmark identification. The
identification of a screwdriver used to pry open a door may seem
mundane when compared to the identification of a homicide bullet, but
it can be just as important in the prosecution of criminal cases such
as burglaries.
Improper collection and handling
of firearms and tools can diminish their usefulness for identifying
impression evidence made by them. Toolmarks and expended bullets are
particularly susceptible to damage if handled improperly. The
Identification Technicians of the Crime Scene Unit are trained to
collect firearms and tools, as well as expended bullets and cartridge
casings, and toolmarks, in a manner that does not damage them.
Other common forensic
examinations involving firearms are:
-
Distance determination of a
firearm from the target,
-
Terminal ballistics (gelatin
testing),
-
Function testing (useful in
accidental shooting determinations)
-
General Rifling
Characteristics (GRC) determination, which provides the probable
identity of a firearms model based on the measurement of class
characteristics found on fired bullets and cartridge cases.
NIBIN (IBIS) Services
The National Integrated Ballistic
Information Network (NIBIN) is a joint FBI-ATF-Local resource program
that enables participating law enforcement agencies to store
shooting-related data and test-fire exemplars from recovered firearms
in one common system capable of performing comparisons and producing
probable matches. Using the automated ballistics imaging technology
of the Integrated Ballistics Identification System (IBIS), a network
of repositories for all crime guns has been developed that parallels
the Automated Fingerprint Analysis System (AFAS) system maintained by
the FBI and used by CalID.
Images of bullets and cartridge
casings from crime scenes, as well as test-fired bullets and cartridge
cases from firearms seized by law enforcement, are entered into IBIS,
which then compares them to similar images in a database maintained by
the Bureau of Alcohol, Tobacco, and Firearms. Probable matches, or
“cold hits,” from other IBIS sites in California are automatically
reported back by ATF. Several thousand “cold hits” have been achieved
nationwide by the system since its inception in the early nineties.
The Forensic Laboratory possesses
one of the five IBIS terminals in the valley. The other three are
located at the California Department of Justice Laboratory in Fresno,
Stockton Police Department, the Kern County District Attorney's Crime
Lab in Bakersfield, and the Sacramento County District Attorneys Crime
Lab in Sacramento. The IBIS site in Kern County is connected to the
NIBIN network in the Los Angeles area. The other four IBIS sites in
the valley, as well as others in the Bay Area and Reno, share a common
network administered by the ATF Laboratory in Walnut Creek,
California.
The Forensic Laboratory currently
test-fires and enters into IBIS every firearm seized by Fresno Police
Department and the Fresno County Sheriff’s Office. Other Fresno
County law enforcement agencies submit their firearms and related
evidence to the DOJ Fresno Laboratory for entry.
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