Forensic Services Division

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 Photo of Forensic Services Offices

The Forensic Services Division (FSD) exists to provide the public with the highest quality of service in the recognition, collection, preservation, scientific analysis, and interpretation of physical evidence, and its presentation in court.  Towards this purpose, the laboratory is dedicated to serving the interests of justice to the best of our ability.  The FSD has been an accredited laboratory since 2003.  Please see for more information about our accredited disciplines and scope of services.


The Forensic Services Division consists of the following major components:

Summit Laboratory

2530 Arnold Drive, 2nd Floor
Martinez, CA  94553
Phone: (925) 335-1600
Fax: (925) 335-1601

Photo of Forensic Services Staff Analyzing DNAForensic Biology (DNA)

Scientists in the Forensic Biology Unit routinely examine evidence for the presence of biological material and its suitability for the DNA analysis process. 

 Biological Screening

Some cases start with a screening process to determine if probative biological fluids may be present on an item of evidence by utilizing several presumptive and confirmatory tests. Screening is used primarily on sexual assault and homicide evidence to deduce if any stains or samples may have forensic significance to the case at hand.

The Forensic DNA Process

After the screening process, or for casework in which biological fluids may not be present (e.g., items that have only been touched or handled by a suspect), the evidence can move forward for DNA analysis. In general, the DNA analysis process follows five steps:

  1. Digestion and Extraction: A portion of evidence is placed in a tube, and the addition of a series of chemicals allows the DNA to be released from the cells and purified.
  2. Quantification: The sample is run on an instrument to determine how much DNA starting material is present. This is a necessary step for downstream processing.
  3. Amplification: Using polymerase chain reaction (PCR) technology, fragments of the DNA sample called short tandem repeats (STRs) are copied millions of times in order to be analyzed by the capillary electrophoresis instrument in the next step.
  4. Capillary electrophoresis: An electrical current is applied to the DNA fragments from each sample to allow separation by size as the fragments pass a detector. A printout of the STR DNA peaks detected is created, known as an electropherogram.
  5. Analysis: The electropherogram is interpreted by the DNA analyst to give meaning to what DNA was detected. The analysis can answer questions such as: is DNA from one or multiple persons? If it is a mixture, is the DNA from one donor in a much higher amount than others? Is the DNA of good quality?

After these steps are completed, conclusions may be drawn as to the possible contributor(s) of the genetic material left on the evidence. DNA is unique to each individual (with the exception of identical twins) allowing comparisons to be made between evidence items and the DNA profiles from known individuals. In cases in which a suspect has not yet been identified, or a potential suspect has been eliminated by comparative DNA analysis, the unknown DNA profile can be entered into a database known as CODIS.


The Combined DNA Index System (CODIS) blends forensic science and computer technology into a tool forCODIS Logo linking violent crimes.  The Forensic Biology (DNA) Unit uses CODIS to exchange and compare DNA profiles electronically, between local, state and federal agencies, linking crimes to each other and to criminal offenders.  Analysts use CODIS to search DNA profiles obtained from evidence against DNA profiles from crime scenes, convicted offenders, and arrestees. CODIS is administrated by the Federal Bureau of Investigation and enables police from multiple jurisdictions to share leads and coordinate their investigations.

Recent Improvements in the Biology Unit

The Forensic Biology Unit embarked on a Lean Six Sigma improvement program to increase laboratory efficiency and throughput in the DNA analysis process.

The Biology Unit now offers male specific DNA testing (Y-STR typing). This technology is especially useful for sexual assault evidence with a high ratio of female to male DNA.

New Technologies Coming Soon

The Biology Unit has been in a continuous state of improvement, always seeking the latest technology and methods of DNA analysis. Several instruments and software are currently in the process of validation for implementation in future casework.

The Versa liquid-handling robot will automate and increase the processing throughput for sexual assault evidence.

The ANDE Rapid DNA instrument will allow for “sample in, profile out” analysis of reference DNA samples in as little as 90 minutes.

The FSD is working to bring sophisticated software available for mixture deconvolution online in 2020. This software will aid scientists with DNA mixture analysis using complex mathematical modeling in cases that may have previously been deemed uninterpretable.

Cold case consultations

The Unit offers free consultations for agency’s cold cases.  Please make an appointment and bring your case file.  The Unit can help strategize the best course of DNA Analysis for your evidence.  We can tell you what evidence has been consumed, should be re-analyzed, as well as, whether any evidence may be amenable for a CODIS familial search and/or a genealogical search.

Photo of Firearm and Tool Comparison work being performedComparative Evidence (Firearm and Tool Comparisons)

The Comparative Evidence Unit analyzes firearms for operability and compares bullets, cartridge cases, and shotshell cases to determine if they were fired from the same firearm, multiple firearms or specific firearm if submitted.  Firearms are examined to determine operability of the safety features, physical characteristics of the firearm, determination of manufacturer, model and serial number. A microscopic comparison of ammunition components is done to associate a particular firearm as having fired the components.


The Comparative Evidence Unit utilizes the National Integrated Ballistics Information Network (NIBIN)Photo of the Comparative Evidence Unit utilizing the National Integrated Ballistics Information Network administered by the Bureau of Alcohol, Tobacco, Firearms, and Explosives. Digital images from the markings on fired cartridge cases (shell casings) located at a crime scene or test fires obtained from recovered firearms are uploaded to the NIBIN database and searched regionally. NIBIN Leads are reported to the requesting Agency, the local CGIC and ATF members within 24-48 hours of searching.  The FSD typically finds that the same gun was used in several shootings from within and outside the County.  Often, a recovered firearm may be linked to not only previous shootings but to homicides as well, providing critical information to investigators.  The NIBIN Program in partner with CGIC (Crime Gun Intelligence Center) has a stated goal of disrupting the shooting cycle. It can only be achieved through a collaborative effort between Law Enforcement, the Lab and the DA’s Office.  NIBIN is the only interstate automated ballistic imaging network in operation in the United States.

Photo of Forensic Services staff member utilizing Latent PrintsLatent Prints

Latent prints are impressions or marks produced by the raised skin, known as friction ridges, on human fingers, palms, and soles of the feet. Latent prints are among the most valuable and common types of physical evidence found at crime scenes. A variety of techniques that includes the use of chemicals, powders, lasers, alternate light sources, and other physical means, are employed in the detection and development of latent prints. The primary function of the Latent Print Unit is to develop and recover latent prints from items of evidence, compare them to known exemplars, and conduct local and national database searches.

When latent prints are recovered or the evidence submitted is examined, analysts are able to: screen for the presence and quality of the prints; compare and identify or exclude the prints of value with the known prints of suspects or others listed for elimination purposes and decedents; or search the print via the Automated Biometric Identification System (ABIS) to produce a potential lead in the case.  The process for associating latent prints and known prints involves four phases known as Analysis, Comparison, Evaluation, and Verification, also known as ACE-V. Analysis refers to the initial information gathering process in which the analyst assesses the quality and quantity of discriminating detail present in the latent print. If the latent print has sufficient information, the analyst compares the detail in the latent print to known fingerprints and palm prints. In the evaluation phase, the analyst assesses the level of agreement or disagreement between the latent print and the known prints and renders a conclusion. Verification is the review of the analyst’s conclusion by another qualified analyst. The Latent Print Unit provides expert witness testimony in local and federal courts and training to law enforcement agencies on various latent print topics that include processing evidence at crime scenes and different methods to obtain high quality friction ridge detail.

Automated Biometric Identification System (ABIS)

ABIS is a sophisticated computer-based system which electronically encodes, searches, and stores thePhoto of Forensic Services staff member utilizing Automated Biometric Identification System images of fingerprints and palm prints.  “Known prints” or exemplars comprise a complete set of fingerprints and palm prints taken from a known individual. Typically known prints are obtained using a Livescan device. The analysts in the Latent Print Unit use ABIS as a tool to search unknown latent prints against the known prints in the database. The ABIS software looks for details in the print to find the best match in its database.  Any potential matches or “hits” are evaluated by an analyst.  Prints that do not “hit” will continue to search in the database.

Crime Scene Response

Photo of Crime Scene Responder Filling out PaperworkCrime scene responders are responsible for complex crime scene investigations using various types of equipment; developing, securing, and packaging physical evidence for scientific evaluation and comparison; preparing detailed reports on the observations and activities at the scene and testifying in court regarding the findings and processing methods used at the scene. Crime scenes may be documented by the RTC360, a 3D laser scanner with the ability to quickly scan the scene with full HDR images. The resulting output, a TruView, allows law enforcement and the district attorney’s office to visualize the scene as never before.

Digital Evidence

Digital media permeates modern life. Cameras in our cell phones, home security, doorbells, cars and appsPhoto of Forensic Services staff member on computer that track our every move can also record crimes. Digital evidence is becoming a more common component of crime solving as technology spreads.

The Digital Evidence Unit specializes in enhancing audio, video, and image files to extract information for investigators. We use the latest software to enhance videos and images for suspect license plates, faces, and other identifying information. We can filter out background noise and enhance conversations from audio recordings.

The Digital Evidence Unit uses sophisticated tools on modern evidence to help our law enforcement agencies solve crimes in our high-tech world.


Muir Laboratory

1960 Muir Road, 2nd Floor
Martinez, CA  94553
Phone: (925) 313-2800
Fax: (925) 313-2840

Drug Analysis

Photo of Drug Analysis being PerformedExaminers in the Drug Unit analyze powders, solid materials, liquids, plant material, mushrooms, blotter paper, and food items for the presence of controlled substances.  In addition, the Unit examines pharmaceutical preparations in the form of tablets, capsules, and patches.  Controlled substances are routinely screened using color tests with confirmation performed by gas chromatography/mass spectrometry (GC/MS) or Fourier Transform Infrared Spectroscopy (FTIR) coupled with Attenuated Total Reflectance (ATR).


The Alcohol Unit is split into blood/urine analysis and breath alcohol duties.  The blood/urine analysisPhoto of Alcohol Analysis being performed consists of analyzing blood and urine samples in connection with DUI cases using Heated Headspace Gas Chromatography with Flame Ionizaion Detector (HSGC/FID).  The breath alcohol duties include training and licensing breath test operators, responding to requests for records, providing testimony in courts of law on analysis and effects of alcohol, and maintaining the evidential breath testing instrument (Intoximeters DMT Dual Sensor) used in Contra Costa County.


Photo of Toxicology Analysis being performedThe Toxicology Unit receives biological samples from law enforcement agencies for a variety of offenses, including DUI investigations.  The unit will be expanding DUI/DUID testing with the introduction of new screening and confirmatory instrumentation.  The Randox Biochip technology will allow the unit to expand screening from 6 to 20 analytes.  The confirmatory testing will continue to include GC/MS and introduce Liquid Chromatography/Mass Spectrometry (LCMS) instrumentation and expand the number of analytes as well as sensitivity in confirmations. While statutory limits exist for alcohol none are set for other drugs; consequently, expert toxicology testimony regarding the effects of drugs on human performance and driving behavior is often necessary to establish impairment.

Photo of woman lifting box

Property & Evidence Services

2099 Arnold Industrial, Suite D
Concord, CA  94520
Phone: (925) 646-5877

Public Property Hours: Monday - Friday, 8:30 AM to 4:30 PM

To bid on property click here.

Property and Evidence Services

Property and Evidence Services is responsible for the property handling of all Sheriff’s evidence, contract cities, station houses, and courts.

Proper handling includes receiving processing, packaging, tape sealing, storing, releasing and the disposition of all items taken in as evidence. This includes safekeeping and found property.  Property is responsible for protecting the integrity of its evidence from cradle to grave.

Training Opportunities

The FSD offers a wide variety of training opportunities (e.g. CSI brush-ups, DMT breath instrument, Drug Presumptive Testing, and more). For more information, please inquire at the Summit or Muir laboratory for upcoming training dates.

Customer Service

Reported results can be found on ARIES.

Management of the FSD is committed to good professional practice, to the quality of our testing, and serving our customers.

The FSD welcomes feedback from our customers. We are hopeful you will complete a testing or training survey to help us gain insight into the quality of our services and what we can do to improve. Thank you for your time. We appreciate any feedback you can share with us.

In service to our customers, the FSD will:

  • Listen to comments, suggestions, and concerns in an effort to improve our services and to meet customer needs
  • Cooperate with customers and their representatives to clarify their request, to provide them the information they need, and to deliver a quality work product
  • Select the most appropriate test methods for the customer based on the requested service and use test methods that are valid, appropriate, and meet the needs of the customer
  • Share results of testing when required to do so. Examples include sharing results with another forensic laboratory to complete a request analysis or in a technical presentation
  • Send evidence to a competent external laboratory if the requested analysis cannot be performed in-house.
  •  Release records when compelled to do so. Examples include complying with discovery requests, court orders, or for accreditation activities