Measuring dimensional and morphological heat alterations of dismemberment-related toolmarks with an optical roughness metre

Area of Science:

• Forensic Science
• Forensic Pathology
• Bioarchaeology

Background:

• Sharp force trauma analysis is critical in forensic investigations.
• Understanding post-mortem changes, such as burning, is essential for accurate interpretation of bone injuries.

Purpose of the Study:

• To investigate the effects of fire exposure on sharp force trauma toolmarks on juvenile pig long bones.
• To quantify changes in toolmark dimensions (length, width) and morphology (roughness, floor shape) after burning.

Main Methods:

• Induced toolmarks on pig bones using a bread knife, serrated knife, machete, and saw.
• Burnt bone samples in a chamber furnace.
• Analyzed toolmarks using 3D optical surface roughness metrology before and after burning.
• Performed statistical analyses including t-tests and ANOVA.

Main Results:

• Fire exposure consistently decreased toolmark length and increased roughness.
• Toolmark width showed minimal changes, with slight shrinkage for bread knife marks.
• Floor shape morphology varied post-burning, particularly for knife-induced marks.
• Serrated knife and machete toolmark metrics showed no significant variations after burning.

Conclusions:

• Fire exposure alters sharp force trauma signatures on bone but does not eliminate their identifiability.
• The degree of distortion depends on the weapon type, trauma characteristics, and burning conditions.
• Preservation of class features in burnt bone trauma is influenced by these factors, impacting forensic casework.