The Sheriff's Office Forensic Laboratory has been existence for over 30 years. It was created in the early days of forensic science in the state of California. Over the years the lab has grown from a one man operation to seven Criminalists that cover the various analysis within the laboratory. The laboratory started with only two types of analysis, Drug and Serology analysis. This has grown over the years to cover the major disciplines of forensic science. The Forensic Laboratory consists of the following units:
- DNA/Serology
- Firearms/Toolmark
- Narcotics Analysis
- Crime Scene Reconstruction
The Director of Forensic Services executes overall supervision of the Forensic Laboratory and reports directly to the Detective Bureau Captain and is part of the Sheriff's Office Command Staff. Crime Scene Reconstruction is a collaborative effort by all sections of the Laboratory, Crime Scene unit personnel and Detectives. Supervision of these cases are assigned according to the particular needs of the case.
Mission and Objectives
The stated mission of the Forensic Laboratory is to provide for its clients the timely, accurate, and reliable scientific examination of physical evidence, followed by the clear, unbiased and objective interpretation of analytical findings.
The objectives of the Laboratory are:
- To provide forensic analysis, interpretation, and testimony to law enforcement agencies and courts within Fresno County.
- Establish a system of case prioritization, which takes into account the needs of the Sheriff's Department and the Criminal Justice System.
- Provide an unbiased, scientifically objective work product that is responsive to the Sheriff's Department and the Criminal Justice System.
- Maintain an integrated approach to the evaluation of case material.
A program of ongoing training, proficiency testing and quality assurance serves to further the goals and objectives of the Laboratory and its mission.
DNA and Serology
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).
Unlike the older conventional serology systems, which were generally limited to the typing of blood, saliva, and semen, DNA analysis 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 used 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 analyst; the two Criminalists in the Forensic Laboratory specializing in this technique hold Masters of Science degrees, in addition to the Bachelor of Science degree normally required of a Criminalist.
The DNA analysis system, called STR (Short Tandem Repeat) is currently being used with an eight channel capillary electrophoresis genetic analyzer. This method will effectively allow conclusive identification of individuals. The chances of finding two persons with the same DNA type in the STR system are approximately one in a 700 quadrillion or greater than 1000 times the population of the earth.
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 measuring 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 ten earth populations.
Firearms/Toolmark Unit
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 lab also provides research and testing services of duty ammunition for the Sheriff's Department and shooting scene reconstruction.
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. 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.
Other common forensic examinations concerning 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 probable firearms model identity based on the measurement of characteristics found on fired bullets and cartridge cases.
Ammunition Testing
A little-known service performed by the Forensic Laboratory is the ballistics gelatin testing of duty ammunition for the Sheriff's Department. This testing was a crucial element in the selection of the current duty ammunition for department-issued handguns, the SWAT special weapons, and the recent selection of ammunition for the Sheriff's Department's new carbines.
Controlled Substances
The Forensic Laboratory provides continuous and routine controlled substances analysis service for every law enforcement agency in Fresno County, with the exception of the Fresno Police Department.
The controlled substance analysis program is unique within the State of California, in that virtually every drug sample submitted to the Laboratory for analysis is analyzed, and a report is issued to the requesting agency, within 24 hours it is submitted. A conclusive report of analysis accompanies virtually every controlled substance complaint submitted to the District Attorney's office for filing, freeing the investigator and the prosecutor (as well as the defense attorney) to concentrate on other substantive issues.
The controlled substance analysis program is so rapid and streamlined that the Director of the Forensic Services Section of Scotland Yard visited the Forensic Laboratory to see how it was accomplished!
Conclusion
The Forensic Laboratory consists of dedicated staff members that perform a vital role within the Sheriff's Office. This mission keeps the various units of the Forensic Laboratory very busy. The qualities of the people that work within these units are vial to the investigation of major crimes that occur in Fresno County.