Skin Microbiome Analysis for Forensic Human Identification: What Do We Know So Far?

Abstract

Microbiome research is a highly transdisciplinary field with a wide range of applications and methods for studying it, involving different computational approaches and models. The fact that different people host radically different microbiota highlights forensic perspectives in understanding what leads to this variation and what regulates it, in order to effectively use microbes as forensic evidence. This narrative review provides an overview of some of the main scientific works so far produced, focusing on the potentiality of using skin microbiome profiling for human identification in forensics. This review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The examined literature clearly ascertains that skin microbial communities, although personalized, vary systematically across body sites and time, with intrapersonal differences over time smaller than interpersonal ones, showing such a high degree of spatial and temporal variability that the degree and nature of this variability can constitute in itself an important parameter useful in distinguishing individuals from one another. Even making the effort to organically synthesize all results achieved until now, it is quite evident that these results are still the pieces of a puzzle, which is not yet complete.

Trick or Treating in Forensics—The Challenge of the Saliva Microbiome: A Narrative Review

“…Numerous major advances have been made in the scientific discipline of microbial forensics over the past decade. Most of the studies published so far have been focused on the analysis of the skin microbiome to connect people to an object or a place with important repercussions in the forensic field, shining a spotlight on the possibility of undertaking a microbial forensic investigation to identify the perpetrator of a crime [ 35 ]. The most important questions to be answered by forensic science are usually both “who committed the crime?” and “who did not commit the crime?”.…”

“…As already underlined in the field of skin microbial analysis, in order to gather high quality evidence that can really be utilized for indictment and conviction of the perpetrator of a crime, it is necessary to generate standards and guidelines that allow for the obtaining of statistically and scientifically meaningful results using the same methods under the same circumstances [ 35 ]. As recently pointed out by Neckovic et al [ 36 ], the studies published so far about human microbial composition largely consist of descriptive, rather than functional, analyses of microbiomes.…”

At the Interface of Life and Death: Post-mortem and Other Applications of Vaginal, Skin, and Salivary Microbiome Analysis in Forensics

“…While current research has focused on the potential of the skin microbiome as trace evidence ( Tozzo et al, 2020 ), to the best of our knowledge, only Kodama et al (2019) have investigated whether actual objects from real death scenes (e.g., smoking pipes, medical devices, and phones) could be linked to the hand palm of the deceased through microbiome identification. The skin microbiome on the palm of the deceased remained stable up to 60 h after death, opening a window for individual microbiome identification even after death.…”

Diurnal variation in the human skin microbiome affects accuracy of forensic microbiome matching

“…Despite these successful demonstrations, the analogy between microbiota traces and fingerprints is misleading. Unlike fingerprints, which are generally stable for a person’s entire life and which can persist on a surface unchanged for months to years, a person’s skin microbiome can shift over weeks or months [ 14 , 15 ] due to factors including the person’s physiology, their environment, dispersal from external sources, and stochastic assembly processes (drift), although generally these changes over time are smaller than intrapersonal differences [ 16 ]. With the exception of physiology, traces deposited on inert surfaces are susceptible to the same forces, and may be exposed to ongoing microbial deposition from other sources.…”