Preliminary determination of a priori information for forensic lubricant analysis in sexual assault cases

While mass production of materials provides many benefits to the community, it hinders the potential to source unknown samples in a forensic context. To circumvent this issue, the forensic community has been exploring the use of likelihood ratios to compare two probabilities with the goal of deciding if it is more likely that the unknown sample is from a known source or a different source. To aid in this calculation, it is helpful to understand the prevalence of that item in the local community, which is a determination that can be hindered by mass production. This study aimed to determine the prevalence, including rarity and commonality, of sexual lubricant products in the local area surrounding the University of Central Florida (UNIVERSITY). This information would provide a baseline on the number of products available for purchase in the area that can be used in acts of consensual intercourse or sexual assault. Understanding the products available would also provide insight into the type of chemical compounds that are present within sexual lubricants, which can be used for sourcing purposes. The results of this study revealed several major findings: (i) the physical marketplace around the UNIVERSITY is dominated by water-based lubricants, (ii) lubricant brands may be directly associated with a particular retail store, and (iii) specific chemical compositions of a lubricant product may also be associated with a particular retail store. Providing frequency data and odds information about the lubricant products can assist investigators and forensic scientists in understanding the layout of the local sexual lubricant marketplace, which can assist in determining the uniqueness of the unknown sample recovered in a sexual assault case and potentially provide an investigative lead. Key points  A survey of commercially available lubricant products was conducted.Surveys were conducted at supermarkets, gas stations, grocery stores, etc.Products surveyed informed conditional probabilities for lubricant products.Products surveyed also informed odds statistics that may aid criminal investigators.Information on the rarity of products/lubricant compounds was provided.