Evaluating the Skin Microbiome as Trace Evidence

• NCJ Number: 251647
• Author(s): Rob Knight; Jessica L. Metcalf; Jack Gilbert; David O. Carter
• Date Published: June 2017
• Length: 11 pages
• Grant Number(s): 2014-R2-CX-K411
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored); Program/Project Description

Annotation

This project's objectives were to characterize basic transfer properties to common surface materials of an individual's unique skin microbial community and to determine whether it is possible to characterize an individual's skin microbial handprint after death.

Abstract

The project found that skin microbes detected on ceramic and plastic surfaces were most robustly and accurately linked to individuals. The ability of researchers to recover enough signal to correctly match the person with the touched tile increased with 20 and 30 touches compared to 10 touches. A person's microbial signature persisted on a surface for at least 1 day. The skin microbial communities on a deceased individual still shared unique/individualized microbial communities found on that person's personal objects, whether sampled at earlier or later hours postmortem. By obtaining new information on the transferability, stability, and individuality of human skin microbiomes, this research increased knowledge of physical evidence, thus providing basic information on the conditions under which criminal investigators can match an individual's skin microbial signature to objects or surfaces at crime scenes. This is the first step toward developing these technologies for their future use by crime laboratories. The research was conducted with 13 participants, who touched five material types (plastic, glass, ceramic, metal, and wood). Each material type was touched in sets of five replicates in consecutive order, each touched 10 times. Samples were collected from deceased individuals and surrounding surfaces at five death scenes. Data analysis is explained. 6 figures