High-speed video analysis of forward and backward spattered blood droplets

P. M. Comiskey, Alexander Yarin, D. Attinger

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

High-speed videos of blood spatter due to a gunshot taken by the Ames Laboratory Midwest Forensics Resource Center (MFRC) [1] are analyzed. The videos used in this analysis were focused on a variety of targets hit by a bullet which caused either forward, backward, or both types of blood spatter. The analysis process utilized particle image velocimetry (PIV) and particle analysis software to measure drop velocities as well as the distributions of the number of droplets and their respective side view area. The results of this analysis revealed that the maximal velocity in the forward spatter can be about 47 ± 5 m/s and for the backward spatter – about 24 ± 8 m/s. Moreover, our measurements indicate that the number of droplets produced is larger in forward spatter than it is in backward spatter. In the forward and backward spatter the droplet area in the side-view images is approximately the same. The upper angles of the close-to-cone domain in which droplets are issued in forward and backward spatter are, 27 ± 9° and 57 ± 7°, respectively, whereas the lower angles of the close-to-cone domain are 28 ± 12° and 30 ± 18°, respectively. The inclination angle of the bullet as it penetrates the target is seen to play a large role in the directional preference of the spattered blood. Also, muzzle gases, bullet impact angle, as well as the aerodynamic wake of the bullet are seen to greatly influence the flight of the droplets. The intent of this investigation is to provide a quantitative basis for current and future research on bloodstain pattern analysis (BPA) of either forward or backward blood spatter due to a gunshot.

Original languageEnglish
Pages (from-to)134-141
Number of pages8
JournalForensic Science International
Volume276
DOIs
Publication statusPublished - 2017 Jul 1
Externally publishedYes

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Keywords

  • Backward spatter
  • Bloodstain pattern analysis
  • Forward spatter
  • Gunshot
  • High-speed video analysis
  • Particle image velocimetry

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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