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Typical Evidence Examination Scheme

 

 

 

 

 

 

 Fibers

 Paint

 Adhesive Tape

 Muzzle to Target Distance

 Unknown Materials Identification

 Latent Fingerprint Development


Fibers:

A fiber examination is performed both microscopically and instrumentally.  A comparison of the physical, chemical, and optical properties of an unknown fiber to a suspected fiber source can provide an evidentiary link or can provide important investigative information for a Law Enforcement Agency.

 

Cotton fibers, plane polarized light

Cotton fibers, crossed polars  


 

 

Wool, plane polarized light, notice the presence of scales along the margin of the fiber

Acetate fiber, plane polarized light  


 

 

Acetate fiber, crossed polars

Acetate fiber, oriented NE to SW, "red" wave plate inserted


 

 

Acetate fiber, oriented NW to SE, "red" wave plate inserted

Acrylic fiber, plane polarized light


 

 

Acrylic fiber, crossed polars

Acrylic fiber, oriented NE to SW, "red" wave plate inserted


 

 

Acrylic fiber, oriented NW to SE, "red" wave plate inserted

Acrylic fiber, oriented 45 degrees to crossed polars


 

 

Acrylic fiber, Senarmont compensation to determine retardation value of low birefringent material

Olefin fiber, plane polarized light, notice the presence of pigment within the fiber


 

 

Olefin fiber, crossed polars

Olefin fiber, compensated for retardation with quartz wedge