The Forensic Biology Section of the Forensic Laboratory Division of the Medical Examiner's Office performs serological and DNA analyses on physiological fluids and other nucleated cellular material for the purpose of identification and individualization. The type of material typically examined includes, but is not limited to, blood, semen, saliva, tissue, and "touch" items collected at crime scenes and from articles of physical evidence. Evidence of these types are frequently generated during the commission of violent crimes such as homicides, rapes, assaults, and hit and run fatalities, as well as less violent crimes including burglary, theft and firearms violations. The ultimate goal of the Forensic Biology Section is to identify what type of material is present and then, through the use of DNA analysis, link that material to a specific person.
Upon submission of physical evidence, these items are stored in a secure evidence storage location to await analysis. An analyst is assigned to a specific case and will bring the evidence to the Forensic Biology Section, where it will be documented and analyzed. The evidence will be examined for blood, semen, and saliva staining. An alternate light source is utilized to locate latent staining. Identified stains will then undergo a series of presumptive screening tests. Stains testing positive at this level of analysis will then be subjected to more extensive testing, including confirmatory serological tests and DNA analysis. The DNA profiles generated from these stains will then be compared to known reference samples from victims and suspects. This laboratory currently utilizes two ABI 3130 Genetic Analyzers for this analysis.
Forensic Biology has been revolutionized by DNA STR (Short Tandem Repeats) analysis. STR's offer the advantage of short analysis time, a high degree of discrimination, and the ability to look at small and degraded DNA samples. Samples as small as cellular material left behind by prolonged or aggressive handling (touch evidence) can be compared to possible contributors.
The Forensic Biology section is linked to the FBI CODIS (COmbined DNA Index System) DNA database network. After a DNA profile is obtained, it can be searched against local, statewide, and national law enforcement databases. Through this network the laboratory is able to search an unidentified profile against unsolved case profiles and known profiles of convicted offenders and arrestees throughout the country. These searches can link cases together or provide important investigational leads for investigators on unsolved cases.