Trace Evidence
The Trace Evidence Section is under the supervision of Special Agent in Charge Chuck McClelland.
This section is responsible for the examination of small (trace) particles of evidence left behind in the commission of a crime. The evidence examined includes hair, fiber, paint, glass, arson debris, gunshot residue, and other miscellaneous particles. This type of evidence is often present in rapes, murders, robberies, arsons, hit-and-runs, kidnappings, as well as other crimes.
Several different instruments and instrumental methods are employed in the analysis of trace materials. These include:
Infrared Spectroscopy - Two different Perkin-Elmer Fourier Transform infrared spectrophotometers are used in the Trace Evidence Section. These two instruments are employed in the analysis of paints and other polymers, explosives, fibers, and unknown materials.
Inductively Coupled Plasma/Mass Spectroscopy - This technique, known as GC/Mass Spec, is used to identify arson accelerants and organic liquids. An Agilent Elan DRC-e Inductively Coupled Plasma/Mass Spectrometer is used with a Hewlett Packard 5970 Mass Selective Detector.
Atomic Absorption Spectroscopy - A Perkin-Elmer SIMMA 6000 Atomic Absorption Spectrophotometer is employed to detect components of primer residue in cases that involve the use of a gun. This instrument is also used to detect lead in alcohol and arsenic in various samples.
Pyrolysis/Gas Chromatography - A JHP-22 Curie Point Pyrolyzer is attached to a Hewlett Packard 5890 Series II Gas Chromatograph to analyze polymer samples. Paints, tire rubbers, and other polymers are pyrolyzed and the resulting gas transferred to a gas chromatograph.
Scanning Electron Microscopy - A scanning electron microscope/energy dispersive x-ray system is used for high resolution and magnification imaging with enhanced depth of field. This provides a non-destructive analysis of gunshot residue particles, paints, metals, powders, and other trace materials.
X-ray Fluorescence - A Thermo-Electron Quan-X fluorescence system is used in the elemental analysis of glass, larger metal fragments, powders, and certain liquids.
Microspectrophotometry - Spectral differences in polymeric samples such as paints and fibers are measured with a Nanometrics NANO 100 UVIR Microspot Reflectometer.
X-ray Diffraction - A Rigaku D max B X-ray Diffractometer is used to identify inorganic components in samples with a crystal lattice structure. Samples may include, but are not limited to, arson materials, explosives, paints, powders, and pyrotechnics.
Microscopy - Stereomicroscopes, polarizing microscopes, and comparison microscopes are widely used in trace evidence analysis.