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Bloodstain Patterns on Textile Surfaces: A Fundamental Analysis

NCJ Number
248671
Date Published
January 2015
Length
110 pages
Agencies
NIJ-Sponsored
Annotation
This is a report on a study of factors that influence bloodstain pattern analysis (BPA) on two textile fabrics, an unbalanced 130 x 70 plain woven 100 percent cotton bed sheeting fabric and a 100-percent cotton jersey knit T-shirt fabric.
Abstract
Overall, the study demonstrated that fabrics may interact with, distort, and alter a bloodstain pattern in many different and complex ways compared to bloodstains on hard surfaces. Consequently, additional research is required to bring BPA on textiles up to the standards expected for BPA on hard surfaces. After the blood’s initial impact, the wicking (a bundle, loose twist, or braid of soft threads) determines the pattern of the bloodstain. Asymmetry in the fabric structure can lead to asymmetric synthetic bloodstain patterns. These asymmetric patterns can lead to a stain that appears to come from less than a 90-degree angle, even when a blood drop impacts the fabric’s surface at a vertical 90-degree angle. This might lead to misinterpretation; for example, a passive drop falling onto an unbalanced woven fabric may be wrongly classified as a projected bloodstain. Different fabric constructions and even different yarn manufacturing processes can cause different wicking behavior when impacted by a blood drop or stream. In addition to these factors, the researchers observed that wicking of fabric resulted in a much larger stain than the initial drip stain that occurs immediately upon drop deposition. Differences in bloodstain patterns were also found to be dependent on the surface upon which the fabric was resting. Bloodstain pattern variations are described according to types of surfaces on which fabrics were resting when the blood was deposited. Methodological techniques and issues are described and discussed. Extensive tables and figures and 36 references

Date Created: March 24, 2015