Toolmark variability and quality depending on the fundamental parameters: Angle of attack, toolmark depth and...

Area of Science:

• Forensic Science
• Materials Science
• Statistical Analysis

Background:

• Traditional toolmark comparison relies on subjective visual analysis.
• Objective, automated methods require quantitative statistical data on toolmark similarity and variability.
• Understanding factors influencing toolmark creation is crucial for reliable analysis.

Purpose of the Study:

• To quantitatively analyze parameters influencing toolmark similarity and variability.
• To develop an approach for determining toolmark quality for examiner assistance.
• To compare substrate materials (wax, lead) and creation parameters (angle of attack, depth).

Main Methods:

• Statistical analysis of toolmark similarity and variability for known matching and non-matching marks.
• Experimental creation of toolmarks in wax and lead under varying conditions.
• Assessment of toolmark quality based on preserved structural details.

Main Results:

• Low variability and high similarity observed for matching toolmarks in wax with constant parameters.
• Geometrical details reliably represented down to 10-50μm in wax; 10-25μm for finer details.
• Increasing angle of attack and depth decrease toolmark quality; pushing is better than pulling above ≈45°.

Conclusions:

• Wax is a suitable substrate for experimental toolmarks, reliably capturing details.
• Lead offers finer detail representation but may alter evidence.
• Optimizing toolmark creation (shallow depth, specific angle) enhances quality and aids objective analysis.