Knife cut marks inflicted by different blade types and the changes induced by heat: a dimensional and morphological study

Abstract

Detailed information on skeletal trauma analysis of burned bone is important to ascertain the manner and cause of death in forensic casework. This research used three different knife types, one with a non-serrated blade, one a fine-serrated blade, and one a coarse-serrated blade, to inflict trauma to manually macerated Sus scrofa ribs (n = 240), and these ribs were later exposed to heat. Qualitative and quantitative analyses were conducted using macroscopic and microscopic techniques to assess specific characteristics of the cut marks. Differences in cut mark dimension and morphology of the ribs were investigated. After heat exposure, the cut marks on the rib samples remained recognisable and did not alter considerably. A level of dimensional and morphological preservation was reliant on the cutting action and the features of the knife blade as well as surrounding bone injury. The cut marks inflicted by the non-serrated blade remained recognisable despite exposure to the burning process. However, the cut marks inflicted by the coarse-serrated blade were likely to change significantly when exposed to heat. This study leads to two important results: (1) identification of pre-existing cut marks prior to heat exposure is possible in reconstructed burned bone fragments, and (2) cut marks from different types of knife blades showed dissimilar responses to heat. The outcomes obtained in this study stressed the need to adopt great care with the effects of heat on skeletal trauma analysis.

Survival of sharp force trauma in burnt bones: effects of environmental factors

“…To investigate the effect of environmental factors, 304 Sus scrofa (domestic pig) ribs were prepared. Full details of the methodology for rib preparation, inflicting cut marks, and burning are given in Vachirawongsakorn et al (2022) [ 1 ]. Rib bones were chosen to simulate a stab to the chest scenario.…”

“…Three types of common kitchen knives were used: one with a non-serrated edge, a second one with a fine-serrated edge, and a third one with a coarse-serrated edge (see [ 1 ]). During the cutting procedure, the respective knife was moved with a single back and forth motion perpendicular to the longitudinal axis of the bone surface.…”

“…In a previous paper [ 1 ], the characteristics of cut marks (marks made by the cutting action of a bladed weapon) on bone (pig ribs) caused by three different knives were assessed before and after burning. The study showed that the cut marks could be attributed to the different knife types (non-serrated, fine-serrated, and coarse-serrated) both before and after burning.…”

Interpol review of fire debris analysis and fire investigation 2019–2022

“…Vachirawongsakorn et al examined marks made on bones with different knife blades to determine the effects of heat on the cuts [ 111 ]. Pig ribs were cut 240 times with three different knife types and then subjected to heat.…”

Morphological features of heart damages caused by national Uzbek knives

“…The study of soft tissue objects is a more difficult task for conducting experimental research. Compared to bone objects, which even after exposure to high temperatures can fully convey all the details of a sharp object that caused damage [20], soft tissue objects, such as the heart, can change their dimensions in the postmortem period and thus deform the picture of the damage.…”