Inconclusive Results

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If the evidence and test toolmarks cannot be matched with each other based on individual marks (no sufficient agreement), possible reasons for the inconclusive result include the following:

The toolmarks were made by two different tools.
Damage occurred that caused distortion, deformation, or elimination of microscopic detail in the toolmark.
The tool was damaged, extensively used, abused, or remachined (i.e., sharpened) between the time the two marks were made.
Numerous subclass characteristics may be present.

Potential remedies that could be used in certain circumstances to produce better microscopic detail in test marks include these:

Remount both test and evidence marks end to end on their respective mounts and reexamine them.
“Smoke” the evidence toolmarks with magnesium smoke to enhance detail. This technique is beyond the scope of this training and should be performed only by an experienced examiner.
Prepare additional test marks in a different material, possibly a softer material or material more like the evidence item.
Change the amount, direction, and angle of force employed to create the test marks.

Note:

A study of crime scene documentation and investigative reports often provides insight into the precise orientation of a tool to a toolmarked area at the time the mark was made. This can save considerable time by reducing the number of possibilities.

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