Use of M-Vac system for the collection of trace hairs and fibers

Abstract

Trace evidence is a critical component of forensic investigations and commonly include fibers and hairs. Various methods are used to recover trace materials, including taping, tweezing, scraping, combing, and vacuuming. This study evaluated the effectiveness of the M-Vac™ wet vacuum, as a collection method for recovering trace evidence. The M–Vac is routinely used for the collection of DNA evidence from porous surfaces and has made a large contribution to the forensic science community, but had yet been evaluated for its application in trace evidence recovery. Automotive carpet and bed sheets were stained with whole blood and seeded with trace fibers (polyester and cotton) or hairs (human and dog) to simulate realistic forensic conditions. Samples were collected using the M-Vac system, taping, and dry vacuuming methods. Although the M-Vac system successfully recovered some trace materials, the conventional methods consistently achieved complete recovery. There was observance of some blood transfer subsequent to collection with conventional methods. These findings indicate that the M-Vac system is less effective for trace evidence recovery but may still hold value as a multi-use collection tool in situations when DNA recovery is prioritized. Further research is warranted to determine whether the use of conventional trace evidence collection methods prior to M-Vac sampling influence DNA recovery.