What are the three methods used by investigators to examine fibers?

Answer 1

Whenever a fiber found on the clothing of a victim matches the known fibers of a suspect's clothing, it can be a significant event. Matching dyed synthetic fibers or dyed natural fibers can be very meaningful, whereas the matching of common fibers such as white cotton or blue denim cotton would be less significant. In some situations, however, the presence of white cotton or blue denim cotton may still have some meaning in resolving the truth of an issue. The discovery of cross transfers and multiple fiber transfers between the suspect's clothing and the victim's clothing dramatically increases the likelihood that these two individuals had physical contact.

When a fiber examiner matches a questioned fiber to a known item of clothing, there are only two possible explanations:

• The fiber actually originated from the item of clothing, or
• The fiber did not originate from the item of clothing.

In order to say that the fiber originated from the item of clothing, the clothing either had to be the only fabric of its type ever produced or still remaining on earth, or the transfer of fibers was directly observed. Since neither of these situations is likely to occur or be known, fiber examiners will conclude that the fibers could have originated from the clothing or that the fibers are consistent with originating from the clothing. The only way to say that a fiber did not originate from a particular item of clothing is to know the actual history of the garment or to have actually observed the fiber transfer from another garment.

It is argued that the large volume of fabric produced reduces the significance of any fiber association discovered in a criminal case. It can never be stated with certainty that a fiber originated from a particular garment because other garments were likely produced using the same fiber type and color. The inability to positively associate a fiber with a particular garment to the exclusion of all other garments, however, does not mean that the fiber association is without value.

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