Oklahoma, www.OK.gov OSBI Homepage

Skip Nav Skip to Search
FAQs  |  Contact  |  Site Index








OSBI Tipline get adobe reader
Lab_Forensic_Chemistry_Banner

 

 

Forensic Chemistry-Trace Home

Forensic Chemistry-Trace Information

Forensic Chemistry-Trace FAQ’s

Forensic Chemistry Resources

Contact Us

Laboratory Forms

OSBI Forensic Science Services Home

 

Forensic Chemistry-Trace Evidence Information

 

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 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.

 

View of Acrylic Fiber under Microscope 40x

 

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 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.  

 

Picture of Paint Layers

 

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.

 

Example of Fracture Match (Glass)

 

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.

 

Picture of House on 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.  

 

SEM view of GSR 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.  

 

Roll of Duct Tape