Since human skin and mucosal surface microbiome have a unique signature that is a composite of all the physical and environmental interactions of a human throughout her/his life, this study characterized the microbiome left behind by "invaders" (not regular inhabitants) of properties in Chicago and Fort Lauderdale to simulate offenders present at mock crime scenes of residential burglaries.
The study recruited "home owners" and "invaders" in the two cities for the purposes of determining the length of time a home invasion has to occur for the microbiome of an "invader" to be detected; whether wearing gloves interferes with signature detection; and whether the lifestyle traits of "invaders" can be detected. Researchers sampled the hand and nasal microbiome of "home occupants" (including cats or dogs) and of the "invaders." Up to 10 home surfaces were sampled, including floors, door knobs, and countertops. A dry cotton swab was rubbed over each of these surfaces for 10 seconds, turning the swabbed head to collect as much biomass as possible. Surface texture, time, and location in the household were recorded for each swab. "home occupants" swabbed their nose and dominant hand, and samples were taken from their children and pets in the home. Microbiota samples were collected and stored on "dry ice" during shipment to the laboratory, where they were stored at -80 degrees centigrade until DNA extraction. This study determined that unique and identifiable taxa can be identified that are distinctive to an individual who spends time in a particular space. This means that a crime scene must be protected from contamination by police, crime-scene investigators, and others who might have entered the scene after the crime occurred. Compared to residual human biological material, bacterial cells and their inherent genetic and taxonomic signatures are more likely to withstand decomposition and degradation by the environment. 1 figure