Pinellas County Forensic Lab -
Forensic Science Disciplines
The Pinellas County Forensic Laboratory provides forensic analyses to the criminal justice community following forensic areas:
Controlled Substance Analysis: Seized Drugs Drug Analysis
The chemistry section of the laboratory performs in excess of 10,000 controlled substance analyses each year. Pills, powders, liquids and plant materials that are seized by law enforcement and are suspected to contain a controlled substance, as defined by Florida Statute 893, are submitted for analysis.
The laboratory performs a series of chemical and instrumental tests to determine the identity of any controlled substances present. The laboratory uses state-of-the art instrumentation including gas chromatographs, mass spectrometers, and infrared spectrophotometers in the identification process.
Toxicology: DUI and Sexual Assault
The Toxicology Section receives 700 to 800 DUI cases each year. The law enforcement agencies submit blood and/or urine from suspects in DUI investigations and victims in sexual assault investigations.
In DUI analysis, the specimens are tested for the presence of ethanol and other volatile compounds using Headspace Gas Chromatography. Immunoassay (ELISA) and basic drug analyses are used to screen the specimens for the presence of hundreds of drugs of abuse including oxycodone, alprazolam, cocaine, methamphetamine, marijuana and heroin. Drugs are confirmed and quantitatively measured using gas chromatography-mass spectrometry.
In sexual assault toxicology analysis, blood and or urine specimens collected from the victim are screened for the presence of impairing drugs and drugs commonly associated with drug facilitated rape.
Toxicology: Post Mortem Analyses
At the request of the medical examiner, the laboratory also provides ethanol and drug analysis to assist in the determination of cause and manner of death.
Biology: Serology and Deoxyribonucleic acid (DNA)
The biology section of the laboratory performs serological screening for the presence of body fluids including blood, semen and saliva. These results are used to identify stains for DNA analysis.
DNA Evidence is an integral part of the discovery process in the following cases:
- Poison pen letters
- Breaking and Entering
- Weapons investigations
- Decedent identification
DNA is the genetic material present in the cells of all living organisms and is virtually unique to each individual, excluding identical twins. Although comparatively unique, DNA is the same within every cell in a human that contains a nucleus; as such, the DNA in a person's blood is the same as the DNA in their skin cells, semen, saliva, tissue, organs, hairs, teeth, bone and a variety of other materials. This fact is critical in criminal investigations, in which a profile gleaned from biological material found at a crime scene is compared to a known suspect profile or with a database of existing profiles. If the profiles match at a set of specific DNA regions (markers) then a statistical probability is determined of the likelihood that another person contributed that DNA. For example, the likelihood that any two individuals (except identical twins) will have the same 13-loci DNA profile can be as high as 1 in 1 billion or greater.
DNA is somewhat fragile. It can degrade over time or in the presence of heat. Additionally, it can be inhibited by the presence of some chemicals or other organisms.
- STR DNA Anaylsis - allows us to evaluate specific regions (loci) that are found on nuclear DNA. The variable (polymorphic) nature of the STR regions that are analyzed for forensic testing intensifies the discrimination between one DNA profile and another. Profiles developed from samples can be uploaded and searched against the CODIS database . CODIS (Combined DNA Index System) allows the analysts to search unknown profiles against convicted offender profiles from across the county. CODIS has been extremely beneficial in solving crimes.
- Y-STR Analysis - is a type of DNA analysis that is limited to the Y-chromosome. These Y-chromosome markers target only the male fraction of a biological sample; therefore, this technique is utilized when a laboratory detects complex mixtures (multiple male contributors) within a sample and is particularly valuable in rape investigations. Because the Y chromosome is transmitted directly from a father to all of his sons, it can also be used to trace family relationships among males.
- Mini-STR Analysis - is an enhanced DNA technique that is more amenable to DNA profile development in degraded or inhibited samples.
Fire Debris Analysis
The chemistry section also performs analysis on evidence related to fire investigations. Fire investigators, using investigative techniques, fire pattern recognition, and accelerant detection canines submit evidence for analysis. The forensic laboratory is tasked with determining if any ignitable liquids are present in the samples submitted.
Fire debris evidence is most commonly submitted in the form of charred debris or other articles from the fire scene or suspect. Volatile residues are separated from the debris samples and analyzed using gas chromatography-mass spectrometry.