NCJ Number
213438
Journal
Journal of Forensic Identification Volume: 56 Issue: 2 Dated: April 2006 Pages: 210-221
Date Published
April 2006
Length
12 pages
Annotation
This article presents findings from a study that sought to determine the size of the smallest parent (first drop) bloodstain produced by gravity-induced drips from three sources (knife tip, nail tip, and hypodermic needle) onto linoleum, cloth, tile, and carpet, without regard to the falling height.
Abstract
The study found that the size of any parent bloodstain that is created from a gravity-induced drip is equal to or greater than 3 mm, including stains that are produced on significantly absorbent targets (e.g., carpet). If the surface is not absorbent, the size of the stain is equal to or greater than 4 mm. Thus, when presented with a bloodstain pattern that includes a number of individual spatter stains that are less than 3 mm, the analyst should conclude that a drip mechanism is excluded as the source event for the stain. The analyst should also consider the stains caused by repetitive blood droplets and any satellite stains. As with all satellites, the volume of blood that is present in any follow-on drop is much smaller than the parent droplet. These small-volume drops fall to the target and land in proximity to their parent stains. These drops will be smaller than the parent stain. This study did not attempt to establish the variations in size for any satellite stains. A minimum height of 3 inches was chosen for all study drops. Three mechanisms for drip creation were devised. The first two were representative of typical crime scene circumstances and involved drips from a knife tip and drips from a fingernail. Although not as typical of crime scenes, a hypodermic needle was introduced as the third crime-scene mechanism. Linoleum, cloth, tile, and carpet were the surfaces used to receive the drops. 4 tables, 4 figures, and 2 references