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Forensic Biology
The OSBI Forensic Biology discipline is a discipline of the OSBI Criminalistics Services Division housed at two locations in the state.
Forensic Science Center in Edmond, Oklahoma
Northeast Regional Laboratory in Tahlequah, Oklahoma
The Forensic Biology discipline specializes in the identification of body fluids and deoxyribonucleic acid (DNA) analysis of samples collected in criminal investigations.
Serology Testing:
- Identification of body fluids including
- Blood
- Seminal Fluid
- Screening of Hairs for DNA
Deoxyribonucleic acid (DNA) Analysis:
- Nuclear DNA Testing (STR)
- Male Specific DNA Testing (Y-STR)
- Criminal Paternity Testing
- Screening of sexual assault kits for male DNA (Y-screening)
The OSBI Forensic Biology discipline analyzes evidence differentiated into the following categories:
Major Crimes
Major crimes consist of violent crimes such as assaults, sexual assaults, criminal paternity cases, and homicides.
Property Crimes
Property crimes consist of crimes that are non-violent such as burglaries and auto theft.
Cold Case
Cold cases are cases in which all reasonable leads have been exhausted.
Combined DNA Index System (CODIS)
The Forensic Biology Unit works in conjunction with the Combined DNA Index System (CODIS) Unit to enter appropriate evidentiary samples into the National DNA Index System (NDIS).
The CODIS Unit also processes eligible offender samples from the State of Oklahoma for entry into the national database.
Specific Requirements for Evidence Submittal for the Forensic Biology discipline:
The following are case requests that are typically not accepted in the OSBI Forensic Biology Unit:
- Animal and plant DNA analysis
- No suspect DNA analysis which does not meet CODIS eligibility requirements
- DNA analysis of controlled substance evidence
- Felon in possession of firearms
- Touch DNA analysis when the item is known to have been handled without gloves during or after collection
- Contact DNA analysis on airbags
All DNA requests should be submitted with known reference samples from the victim(s), suspect(s) (if applicable), and exclusionary samples as necessary.
For exceptions to cases typically not accepted, please contact Janice Joslin, Director of Criminalistics; Mistie Burris, Criminalistics Administrator; or Grace Helms, Criminalistics Administrator.
DNA Analysis
DNA, the acronym for deoxyribonucleic acid, is the genetic material found in all nucleated cells from the body. In forensic DNA analysis, there are a few important aspects of DNA that make the analysis possible. DNA is the same in a person’s blood as it is in a skin cell. A person’s DNA does not change during their lifetime; therefore, they will have the same DNA when they are born until they die. With the exception of identical twins, a person’s DNA is unique, and no two people will have the same DNA profile. A person’s genetic material is obtained from their biological parents. Half comes from their mother, and the other half comes from their father. The purpose of forensic DNA analysis is to match or exclude DNA to a known individual by comparison to samples obtained from crime scenes (questioned samples).
The forensic DNA analysis process consists of the following areas:
Extraction
The extraction process isolates the DNA molecules from the other cellular material in the sample. The OSBI FBU uses PrepFiler Chemistries from Applied Biosystems in conjunction with the Automated Express Extraction System to perform the extraction process.
Quantification
The quantification process estimates the amount of DNA in the sample for downstream analysis purposes and ensures human DNA is present in the sample. The quantification kits utilized are human specific. The OSBI FBU uses a quantitation kit from Applied Biosystems, the Quantifiler Trio kit. The samples are analyzed with the 7500 real-time PCR (rtPCR) instrument from Applied Biosystems.
Amplification
The amplification process generates billions of copies of a particular sequence from the DNA strand in the sample. This is accomplished using the polymerase chain reaction (PCR). PCR is an enzymatic process in which a specific region of DNA is replicated over and over again to yield many copies of a particular sequence. The amplified areas on the DNA are called short tandem repeats (STRs). These highly variable regions among individuals make them effective for human identification purposes. The OSBI FBU utilizes two amplification kits from Applied Biosystems. The GlobalFiler Amplification kit is used for Autosomal (STR) DNA analysis, and the Yfiler Plus Amplification Kit is used for male-specific (Y-STR) DNA analysis.
Genetic Analysis
The genetic analysis process analyzes the amplified DNA samples using the Applied Biosystem 3500 Genetic Analyzer. The instrument utilizes capillary electrophoresis and CCD detection using laser excitation to separate and detect the short tandem repeat (STR) alleles in the samples. The data obtained from the genetic analyzer is analyzed with GeneMapper ID-X software.
Interpretation and Statistics
Once lab analysis is complete, the data from the crime scene samples is interpreted and comparisons are made to the appropriate known samples. If a match is identified, then appropriate statistical analysis is performed.
Types of Samples for DNA Analysis
The most common types of samples analyzed for DNA are blood, seminal fluid stains, and skin cells (touch DNA) samples.
Note: Touch DNA analysis can be performed on items that would result in skin cells being left on objects due to extended contact. Examples of Touch DNA extended contact items would include some clothing, cigarette butts, straws, bottles, cans, etc.
DNA analysis will not be performed on brief contact items without approval. Brief contact items are those items considered unlikely to contain sufficient transfer of skin cells to the object. Examples of brief contact items would include door handles, countertops, etc.
The service limitations of the laboratory can be found here.
Other types of samples that can be analyzed include; hairs with suitable root material available, saliva, sweat stains, tissue samples, bone samples, and teeth.
Urine, fecal material, and vomit are poor sources of DNA for testing and are not tested by the OSBI Forensic Biology Unit.
If you have specific questions on the suitability of samples for DNA testing, please contact the OSBI Forensic Biology Unit.
Serology Analysis
In forensic casework, serology is the identification of body fluids, such as seminal fluid and blood.
There are two types of tests that are used in forensic serology analysis.
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A presumptive test is a chemical test which, by production of color or light, indicates the presence of a body fluid. It is typically more sensitive and less specific than a confirmatory test.
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A confirmatory test is a test that verifies the presence of a specific compound. It is typically less sensitive than a presumptive test but more specific.
The OSBI tests two categories of body fluids: blood and seminal fluid.
Blood Analysis
The presumptive test used for the detection of blood in the FBU is the Hemastix test from Miles Laboratories. The test consists of a plastic strip with a reagent treated filter paper tab at one end. The tab contains Tetramethylbenzidine (TMB), diisopropylbenzene dihydroperoxide, buffering materials, and non-reactants. Testing the blood stain is conducted by rubbing the stain with the Hemastix strip and adding distilled water to the tab. The reagent pad will turn green or blue-green to indicate a positive test.
The confirmatory test used to confirm the presence of blood in the FBU is the Takayama test. This is a crystalline test that is viewed using a microscope. A small cutting of the stain is placed on a microscope slide, and the reagent is allowed to flow between a cover slip and the sample to saturate the sample. The test is positive if the analyst observes pink or red, rhomboid or needle shaped crystals (microcrystalline characteristics) that exhibit birefringence under plane polarized light. This test will confirm only that blood is present and is not species specific. The test works regardless of the blood being human or animal.
The confirmatory test used to confirm human blood in the FBU is RSID-Blood, an immunological based test, provided by Independent Forensics. RSID-Blood is an antigen-antibody test, using glycophorin A found in the red blood cells. This test is similar in appearance to a home pregnancy test. The sample is placed in the sample window of the cassette and allowed to wick through the cassette. A positive result will be indicated by the presence of two red lines forming on the cassette detection strip. If the test is negative, only one line will form.
Seminal Fluid Analysis
The presumptive test used in the FBU for the detection of seminal fluid is the Acid Phosphate (AP) spot test. Acid phosphatase (AP) is a class of enzymes that can catalyze the hydrolysis of certain organic phosphates. The AP spot test is a color change test conducted by rubbing the suspected stain with a swab or filter paper and adding the AP spot test solution. A positive test result will be indicated by a purple color change observed within two minutes. This test is a presumptive test for the presence of acid phosphatase only. A positive result obtained indicates additional testing is necessary.
The p30 Prostate Specific Antigen (PSA) Immunoassay test is used in the FBU to detect p30. p30 is a protein that is found in high concentrations in seminal fluid; however, it is also found in much lower concentrations in other body fluids such as breast milk, saliva, urine, etc. The OSBI FBU uses the Seratec p30 card, which is a chromatographic immunoassay test that utilizes antigen-antibody reactions. The test is similar to a home pregnancy test and is packaged as a cassette. The sample is placed in the sample window and allowed to wick through the cassette. A positive result for p30 will be indicated by the presence of three pink lines. If the test is negative, only two lines will form.
The confirmatory test available for seminal fluid detection in the FBU is the microscopic identification of spermatozoa. This test is accomplished by taking a small amount of the sample and placing it on a microscope slide. The sample is stained with a two-part stain, commonly referred to as the X-mas tree stain, that aids the analyst in visually identifying the sperm.
Hair Analysis
The OSBI FBU does not perform hair comparisons; however the unit will look at hair to determine if it is a human or animal hair. If the hair is determined to be of human origin, then a determination will be made of the hair to determine if it is suitable for nuclear DNA analysis. The OSBI FBU does not perform mitochondrial DNA analysis; therefore, mitochondrial DNA analysis necessary for a case will be referred to the Federal Bureau of Investigation’s mitochondrial laboratory which may perform the mitochondrial DNA analysis. The OSBI FBU can assist with contacting the FBI regarding case acceptance.
Biology Submittal Tips & Tricks
Do not package any type of biological evidence in plastic bags, tubes, etc. Paper envelopes, paper sacks, or cardboard boxes should be used after allowing evidence to dry. This includes bloody items, sexual assault evidence, contact DNA swabs, and known reference sample (buccal) swabs.
Known reference samples (buccal swabs) should be packaged in a single separate envelope for each individual, and clearly labeled with the name of the individual the swabs were collected from. There is no need to package multiple swabs from one individual separately or to include any other labeling such as “right cheek”, “left cheek”, etc. There is no need to submit more than two buccal swabs from each individual. Please use sterile cotton-tipped swabs, and please do not use CODIS offender collection kits for known reference sample collection.
For complicated cases or cases with a lot of evidence, please call the laboratory before bringing evidence to discuss the case and evidence with a biologist (ask for duty biologist).
If there is a suspect named in the case, please obtain a known reference sample from each suspect prior to submitting any evidence, whenever possible. The laboratory cannot look up DNA profiles of suspects who have previously had their profile entered into CODIS as a convicted offender (i.e. “already in the system”), a known reference sample will need to be submitted for comparison to the evidence.