title: An evaluation of the underlying mechanisms of bloodstain pattern analysis error.
abstract: An experiment was designed to explore the underlying mechanisms of blood disintegration and its subsequent effect on area of origin (AO) calculations. Blood spatter patterns were created through the controlled application of pressurized air (20-80 kPa) for 0.1 msec onto suspended blood droplets (2.7-3.2 mm diameter). The resulting disintegration process was captured using high-speed photography. Straight-line triangulation resulted in a 50% height overestimation, whereas using the lowest calculated height for each spatter pattern reduced this error to 8%. Incorporation of projectile motion resulted in a 28% height underestimation. The AO xy-coordinate was found to be very accurate with a maximum offset of only 4 mm, while AO size calculations were found to be two- to fivefold greater than expected. Subsequently, reverse triangulation analysis revealed the rotational offset for 26% of stains could not be attributed to measurement error, suggesting that some portion of error is inherent in the disintegration process.
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Nima
authors.initials: N
authors.lastname: Behrooz
authors.forename: Lee
authors.initials: L
authors.lastname: Hulse-Smith
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Chandra
mesh_terms: D001801:Blood Stains; D006801:Humans; D057446:Hydrodynamics; D008954:Models, Biological; D010781:Photography; D014783:Viscosity