Trace Evidence


The Trace Evidence Unit examines a wide variety of evidence for the purpose of identification and comparison.  The unit is located at the Milwaukee Laboratory and has two analyst positions.


As the term trace evidence implies, most evidence submitted to the unit is small or microscopic in nature.  The Trace Unit utilizes several types of microscopes and scientific equipment to examine these items.  Typical analytical requests include comparisons of questioned and known samples to determine if they could have a common origin or identification of a substance such as an ignitable liquid.


Comparisons involve analyzing and comparing questioned samples to known sources.  An example of this would be glass from a broken window at a burglary scene to glass found in a suspect’s shoes. Comparisons also include evidence types such as fibers, paint, pressure sensitive adhesive tape and metals.


Identifications of substances may be necessary for investigative purposes or for criminal proceedings.  These include ignitable liquid identification in fire debris, explosive identification in an explosive device or bank dye identification from bank security devices.


The Trace Unit also examines broken objects to determine whether or not they could have been joined at one time.  This is called a physical match.  This type of analysis is often found in hit and run cases in which vehicle parts have been left at a crime scene and an agency wants to know if they came from a suspect vehicle.


Services Provided


Comparative Examinations (Questioned and Known)

- Paint (automotive and architectural)

- Glass

- Fibers and Cordage

- Tapes

- Building Materials

- Unknown Materials (General, Tampering)

- Physical Match



- Ignitable Liquids

- Low Explosives

- Bank Dyes


Due to the varied nature of trace evidence as it relates to a case, we encourage you to call the laboratory to inquire whether analysis is possible, especially if you do not see a specific service listed above.



Trace Evidence Unit FAQ's


Contact Information

For questions regarding the Trace Evidence Unit, refer to the contact information for the Milwaukee Laboratory.