Investigating bloodstain dynamics at impact on the technical rear of fabric. (August 2019)

• Record Type: Journal Article
• Authors: Dicken, L.; Knock, C.; Carr, D.J.; Beckett, S.
• Is Part Of: Forensic science international. Volume 301(2019)
• Page Start: 142
• Page End: 148
• Publication Date: 2019-08
• Subjects: Bloodstain analysis -- High speed video -- Impact dynamics -- Plain woven fabric -- Technical rear; Medical jurisprudence -- Periodicals; Chemistry, Forensic -- Periodicals; Forensic Medicine -- Periodicals; Médecine légale -- Périodiques; Chimie légale -- Périodiques; Gerechtelijke geneeskunde; Gerechtelijke chemie; Gerechtelijke psychiatrie; Chemistry, Forensic; Medical jurisprudence; Electronic journals; Periodicals; Electronic journals; 614.1
• DOI: 10.1016/j.forsciint.2019.05.025
• Languages: English
• ISSNs: 0379-0738

Abstract

Highlights: Blood penetrated to the technical rear of the fabric prior to surface spreading. The penetrated blood spread for no more than 0.6 ms after impact. Penetration of blood to the technical rear was fabric and velocity dependent. Wicking of the blood led to a dry technical rear bloodstain for all fabrics. Abstract: Using high speed video, the impact of blood drops falling at three velocities (1.9, 4.2 and 5.8 ms −1 ) were filmed from both the technical face and for the first time the technical rear of three different mass per unit areas (85.1, 163.5 and 224.6 g/m²) of 100% cotton calico. It was seen that there were two stages in the creation of a bloodstain on fabric; the impact dynamics, followed by wicking along the intra-yarn spaces. In the first stage, once the blood impacted the fabric, blood was visible on the technical rear of the fabrics with the medium and lightest mass per unit area within as little as 0.067 ms after impact. No blood was visible on the technical rear of the fabric with the heaviest mass per unit area following impact or the medium mass per unit area from 1.7 ms −1 impacts. On the technical face of the fabric, the blood drop spread laterally and then receded for 8 ms following impact. The dynamics on the technical face were not affected by what was occurring on the technical rear of the fabric. The bloodstain on the technical rear initially only increased until 0.8 ms following impact. The increase in technical rear bloodstain area was caused by continued movement of the blood through to the rear of the fabric as the blood drop spread on the technical face. Once the impact dynamics were concluded within 8 ms of impact, there was no further change in the bloodstain for the remaining 67 ms of high speed video. Following this the blood wicked into and along the yarns, resulting in a dry technical rear bloodstain on all fabrics at all velocities.