Small Bloodstains on Textiles – What Can They Tell Us? - Archival
This webinar explored the interaction of blood with the multiple structures that occur within a simple textile and how these structures affect small bloodstains.
Original Live Webinar took place on 09/12/2018 One of the most common materials collected from violent scenes and examined by forensic scientists are textiles. Often they are bloodied, and, if the stain is a large saturation stain, the pattern can often provide evidence about what happened and how. However, for small bloodstains, there is no reliable means to interpret which events could have led to creating these stains on textiles, such as clothing, upholstery, bed linens, curtains, and so forth. If a similar event deposits blood onto non-porous materials, the bloodstain pattern analyst can often ascertain what type of event(s) is(are) consistent with the bloodstain pattern. On nonporous materials, the bloodstains observed by the analyst are the same as were present a fraction of a second after the blood was deposited unless they were altered by some additional event or action. However, from the moment blood lands on a textile, the stain begins to change and may continue to change for several minutes while the blood wicks into the textile. The final stain can be very different from the initial stain even when left undisturbed. The bloodstain observed by the analyst may have lost much of the detail of the original staining event and thus provide few or no characteristics for analysis. There are several factors that are believed to be responsible for this: (1) the mechanical response of the blood drop to the stiffness and roughness of the textile, (2) the mechanical response of the textile to the impact by blood, (3) the wetting of the textile by blood, and (4) the wicking of blood (or other liquids) into the textile. We will explore each of these factors individually. In this webinar, we explored each of these factors and show how they affect the resulting stains. We will examine real bloodstains on textiles and the time evolution of their development. The participant came away with a greater appreciation for the complexities of bloodstain development on textiles. Finally, they learned new ways to look at textiles at a scene or during laboratory examination for additional clues about the case. Detailed Learning Objectives: • The participant will learn how yarn structure of a textile dominates the wicking behavior of blood within the textile, where even subtle differences may be important. • The participant will learn that the mechanical response of a textile to the impact by blood may significantly alter the stain appearance. • The participant will learn how the texture of a textile can alter bloodstain formation. This webinar was recorded in its entirety at the time of the Live event in order to capture the one on one interaction with the presenter. Funding for this Forensic Technology Center of Excellence event has been provided by the National Institute of Justice.