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Criminalistics Laboratory

Questioned Documents Unit

Responsible for examining documents to determine the facts surrounding them, their preparation, and their subsequent treatment.  The examination can include; comparison of handwriting or hand-printing; detection of alterations; photocopier and computer manipulation; restoration or decipherment of erased and obliterated writing; visualization of latent impressions; the identification of printing processes; reassembly of shredded documents; the dating of documents and differentiation of inks.

Questioned Documents Comparisons


Serology/DNA Unit

Located at the Hertzberg-Davis Forensic Science Center (HDFSC) and Piper Technical Center, this unit analyzes evidence for the presence of biological material to develop DNA profiles. The analytical process is divided into two primary activities, screening and profiling.  Screening involves examination of evidence items collected from crime scenes to locate biological evidence that is probative to the resolution of the crime.  Once probative biological evidence is located, a DNA profile is developed to compare to a known source, such as a suspect or victim, or uploaded into the Combined DNA Index System (CODIS) for searching against State and Federal databases of known offenders. 


Trace Analysis Unit

Examines, identifies, and/or compares hair, fiber, paint, glass, accelerants, explosives, gunshot residue, shoe/tire and tool impression evidence, hazardous chemicals (clandestine laboratory analysis) and performs analysis of other miscellaneous chemical and physical evidence.


Firearms Analysis Unit

Performs examinations and comparisons of microscopic markings on fired bullets and cartridge cases, serial number restorations, renders firearms safe, scientific field investigations of shooting scenes and provides expert testimony in court.  The FAU enters evidence submitted for image capture and search in the National Integrated Ballistics Information Network (NIBIN) database to compare other crimes or firearms in the NIBIN database.


Field Investigation Unit

Responsible for performing scientific field investigations of crime scenes; including evidence inventory / assessment, written reports on field tests and processes performed.  Follow up activity includes the itemization of evidence into its probative components (e.g., DNA, trace evidence, prints), generating the relevant analytical requests, producing detailed scale crime scene diagrams, consulting with investigators to update the case information and providing expert testimony about the results of their field and follow-up examinations.


Toxicology Unit

This unit is divided into two details: Alcohol and Drugs.  The Alcohol Detail is responsible for analysis of blood and urine evidence samples for the presence of alcohol collected from individuals suspected of driving under the influence of alcohol.  They also maintain 33 desktop and 120 hand-held breath alcohol test instruments owned by the Department.  They frequently testify in court as experts on the effects of alcohol on driving ability.  The Drugs Detail is responsible for the analysis of blood and urine evidence samples for the presence of drugs of abuse collected from arrestees.  They also analyze urine samples collected from sworn Department personnel for the Random Drug Testing Program.


Narcotics Analysis Units 

Located at the Hertzberg-Davis Forensic Science Center (HDFSC) and the Van Nuys Area Community Police Station, this unit is responsible for the analysis of narcotics evidence seized from felony offenders.  This analysis must occur within 48 hours of arrest.  Analytical reports are prepared and transmitted directly to the Office of the District Attorney.