Biology Unit (Primary Examination,
DNA Casework, and DNA Database Sections)
Lisa Smyth-Roam Ph.D., Supervising Criminalist
Desk Phone: (775) 328-2898
Steve Gresko, CODIS Administrator / Supervising Criminalist
Desk Phone: (775) 328-2851
David Jackson, DNA Technical Leader / Supervising Criminalist
Desk Phone: (775) 328-8729
Primary Examination Section
The Washoe County Sheriff’s Office Primary Examination section is responsible for a wide variety of examinations including laboratory tests to locate and identify physiological fluid stains. Specifically, this section can examine evidentiary items for the presence of blood, semen, and/or saliva. Important physiological fluid stains are those that either provide a link (e.g., victim to suspect, suspect to scene) or provide an element of the crime (e.g., finding semen on a vaginal swab in a sexual assault case). With this in mind, certain items of evidence may be excluded from the initial examination.
Sometimes physiological fluid stains are visible to the naked eye. However, special lighting or chemical processing techniques may be employed to search an item of evidence or a crime scene when staining is not readily visible. Luminol is a chemical that can be used to detect trace amounts of blood. It is particularly useful in cases where deliberate cleaning attempts have been made to conceal blood staining at a crime scene. Luminol is applied as a spray so large areas can be quickly screened for blood. When luminol comes into contact with blood it results in the production of light which is visible as a bluish-green glow. Near total darkness is required for this test to be performed. Luminol is relatively non-destructive to the surfaces on which it is applied and to any blood that may be present.
Once a suspected physiological fluid stain is located, it is examined with a quick and sensitive, but non-specific presumptive test to determine if it could be blood, semen, or saliva. If a positive result for the presumptive presence of one of these fluids is obtained then the stain may undergo confirmatory testing and/or be collected for further examination in the
The following stain indication chemicals and techniques may be utilized:
Kastle-Meyer test, Luminol, ABAcard HemaTrace test, Acid Phosphatase test, Microscopic Examination, ABAcard p30 test, RSID-Saliva test and Hemastix test.
Additional physiological fluid stains such as fecal matter, urine, and stomach contents (i.e., vomit) are not examined in the WCSO Primary Examination Section. Should it be necessary for items of evidence to be tested for fluids such as these, please contact the FSD for referral to an outside agency.
In addition to physiological fluid stains, this Section also examines evidentiary items for the presence of hairs. Hair examinations serve best to aid in associating an individual with a location or another individual that they deny being in contact with. Laboratory examination of hairs collected from items or crime scenes begins with a determination of the species of origin, i.e., animal versus human. The source of human hairs in terms of body area origin can also sometimes be determined, i.e., head versus pubic. Furthermore, in some cases it may be possible to determine whether a hair has been forcibly removed. If a human hair is located and it has root tissue present then that root can be collected for further examination in the
Physiological fluid stains should be considered as potential biohazards and treated as such. Protective gear should be worn when appropriate for the collection of stains at a scene. Gloves should be changed frequently to protect evidence from possible contamination when moving from area to area within a scene.
SUBMISSION OF EVIDENCE
Items should not be packaged while still wet or moist. Thoroughly dry all stains and then place the evidence in paper bags, envelopes, or boxes. Please DO NOT place evidentiary samples in plastic bags or containers as this promotes
SEXUAL ASSAULT VICTIM
Kits for collection of evidence from victims and suspects involved in sexual assault cases are available from the FSD free of charge. These kits are distributed to law enforcement agencies and hospitals upon request.
DNA Casework Section
The following kits are used: Plexor HY® Human
Conversely, if the estimated frequency of the matching
The following kits are used: Plexor HY® Human
If a matching male Y
In cases where the biological evidence may be degraded or too small in quantity for the
SUITABLE SAMPLES FOR
Typical items of evidence collected from a crime scene may include but are not limited to the following: bloodstains, saliva stains, and semen stains deposited on virtually any surface; genital, vaginal, cervical, rectal, and anal samples collected on swabs or gauze; toothbrushes; food items; pieces of human tissue or skin; fetal tissue; fingernail scrapings/swabbings; forcefully removed hairs; skin cells deposited on drinking containers or handled items; and clothing.
Biological materials that may not result in successful
SUBMISSION OF EVIDENCE:
When submitting evidence, thoroughly dry all stains and then place the evidence in paper bags, envelopes, or boxes. DO NOT place evidentiary samples in plastic bags or containers as this promotes
All evidentiary samples and appropriate reference standards associated with a case must be submitted to the laboratory before testing can begin. Comparison of
When submitting items for
• Homicide (up to 15 evidentiary samples and 10 reference standards)
• Sexual Crimes (with presence of sperm up to 3 evidentiary samples and 5 reference standards)
• Sexual Crimes (absence of sperm up to 5 evidentiary samples and 5 reference standards)
• Crimes against a person (up to 4 evidentiary samples and 5 reference standards)
• Property crimes (up to 2 evidentiary samples and 5 reference standards)
DNA analysis is not performed on the following types of cases: weapons violations, possession of stolen property, found property, vandalism, controlled substances, and larceny.
DNA analysis on bones or teeth is not available through the Forensic Science Division. The FSD may facilitate the submittal to another lab for testing.
This unit, with the assistance of the FBI, operates a statewide computerized
The state of Nevada requires anyone convicted of a felony and anyone arrested for a felony to provide a
The FBI, in conjunction with the fifty states, established a computer software program called the Combined
The Local, State, and National
All DNA profiles are entered into the State DNA database. For more information on the extent of the entry into the national database is determined by the CODIS system.
For more information on the CODIS System, visit the FBI’s website at the following address: http://www.fbi.gov/about-us/lab/codis/codis-and-ndis-fact-sheet
OUTSIDE LABORATORY TESTING:
Convicted offender samples are sent to an approved and accredited subcontractor for analysis. Subcontractor analysis is 100% technically reviewed by the WCSO Biology Unit prior to entry in the DNA database (CODIS).