This article summarizes the findings and methodology of a research project that tested "very small particles" (VSP) from actual pieces of evidence held by the San Diego Sheriff's Office, applying established analytical and interpretive methods to determine the evidential value of such particles.
The two researchers who conducted this study have a background of research into the forensic value of VSP populations. Their earlier research established the viability of using VSP for two important forensic purposes, i.e., matching an object found at a crime scene to a suspect's vehicle or residence and tracing the recent history of where an object has been. The current study sought to determine the evidential value of VSP profiles found on handguns, cell phones, drug packaging, and ski masks. After sampling and analyzing the VSP populations from the objects, the researchers found that the data were sufficient to permit quantitative associations among specimens. The number of particles recovered was greatest from the plastic drug packaging, intermediate for the cell phones and firearms, and low for the ski masks. Researchers concluded that the evidence type itself is acting as a carrier of the VSP signal that has resulted from its history of exposure to particles. Other items of evidence of any type that have a common history of exposure will also act as carriers of a closely related VSP signal. Thus, VSP on a weapon or tool left at a crime scene can be compared and linked with VSP from a suspect's residence or pocket.