The occurrence of contact traces of blood during medical and forensic examinations

Abstract

The purpose of the study is a theoretical analysis of the available types of contact traces of blood and the establishment of their occurrence at the objects of medical and forensic examinations. Contact marks are formed as a result of the mechanical interaction of two objects, one of which is stained with blood. The literature data allow us to distinguish several types of contact traces of blood: impressions, smears, smearing, «voids», traces in the form of changes in the existing stain from wiping, washing, traces-artifacts from insects. Each type has a mechanism of formation and characteristic features. We analyzed 107 archival medical and forensic examinations. In the examinations in which the material situation of the scene of the incident (5 or more objects) is maximally represented, contact traces were present in 76% of the examinations, which indicates a high occurrence. The following types of contact traces of blood were the most common: smears (29% of all examinations), smearing (22.4%) and «voids» (10.3%). Other types of contact traces were less common.