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Trace Evidence

Trace evidence is based on the principle Edmond Locard developed “Whenever two objects come into contact there is always a transfer of material.” It is recognized as one of the most diverse forensic disciplines as it offers forensic analysis in numerous areas. The OSBI Trace Evidence Section offers analysis in the areas of fiber, paint, physical match, ignitable liquids, pressure tape, and adhesive analysis, gunshot residue, and elemental analysis.

Fibers

Forensic fiber examinations are conducted to determine if potential associations exist among people, places, or things. Textile fibers are easily transferred when contact occurs between two individuals or between an individual and a crime scene. Examination of fiber transfer can help to establish an association between two or more people or between a crime scene and a person. The instrumentation used in fiber analysis includes the Fourier Transform Infrared Spectrometer (FTIR), Microspectrophotometer (MSP), and various microscopes.

Paint

Paint evidence can be useful in cases involving automotive or architectural paint. The evidence gathered can be used to determine if paint chips or smears could have originated from a common source. Automotive paint evidence can be analyzed to determine a possible make/model of an automobile with the assistance of the Royal Canadian Mounted Police Paint Data Query (PDQ) database in instances where the suspect vehicle is unknown. The instrumentation used for paint analysis includes the Fourier Transform Infrared Spectrometer (FTIR), Microspectrophotomer (MSP), Scanning Electron Microscope with Energy Dispersive X-Ray Spectrometry (SEM/EDS), and various microscopes.​

Physical Match

Physical or Fracture match can be thought of as an intricate jigsaw puzzle. The edges of broken or torn objects are used to determine if two or more pieces were once a singular object. Various microscopes and photography techniques can be used to help with a physical match.

Fire Debris

Fire debris analysis can help determine if an ignitable liquid was present in a fire. The collected fire debris or liquid is analyzed using a Gas Chromatograph / Mass Spectrometer (GC/MS). If an ignitable liquid is found, it is classified using the American Society for Testing and Materials (ASTM), E1618, Committee E-30. It is important to remember that ignitable liquids can be totally consumed in a fire, and a negative finding of ignitable liquids does not mean that ignitable liquids were not used in a fire.

Gunshot Residue

Gunshot residue is the residue produced from the discharge of a firearm originating from the primer of the cartridge. This residue can be deposited on the hands and clothing of an individual who has discharged or is near someone who has discharged a firearm. This residue can also be transferred to an individual or object. A Scanning Electron Microscope with Energy Dispersive X-Ray Spectrometry (SEM/EDS) is used to identify elements found in the primer mixture of most firearm cartridges and to visualize the shape of the particles.

Pressure Tape and Adhesive Analysis

Tape/adhesive analysis is used to determine if a common source exists between two or more items of tape evidence. Physical characteristics, as well as chemical composition and even physical match analysis, can be used in this area. The instrumentation used for tape/adhesive analysis includes Fourier Transform Infrared Spectrometer (FTIR), Microspectrophotomer (MSP), Scanning Electron Microscope with Energy Dispersive X-Ray Spectrometry (SEM/EDS), and various microscopes.

 

Resources

Contact

Forensic Science Center
800 East 2nd Street
Edmond, OK  73034
Phone: 405-330-6724
Fax: 405-330-6207

Forensic Chemistry Unit Technical Manager
Heather Schafstall
Phone: 405-330-6724
Email: heather.schafstall@osbi.ok.gov

Eastern Regional Laboratory
701 W. Carl Albert Parkway
McAlester, OK 74501
Phone: 918-423-6672
Fax: 918-423-7586

Forensic Chemistry Unit Supervisor
John Giles
Email: john.giles@osbi.ok.gov

Northeastern Regional Laboratory
1995 Airport Parkway
Tahlequah, OK 74464
Phone: 918-456-0653
Fax: 918-458-0037

Forensic Chemistry Unit Supervisor
Joe Orcutt
Email: joseph.orcutt@osbi.ok.gov

Northwestern Regional Laboratory
1305 E. Owen K. Garriot Road
Enid, OK 73701
Phone: 580-242-2600
Fax: 580-234-8707

Forensic Chemistry Unit Supervisor
Anthony Goldman
Email: anthony.goldman@osbi.ok.gov