Forensic Microbiology and Criminal Investigations
by Douglas Ankney
According to microbiologists, every individual has a “unique community of microorganisms on and within their body.” These communities, known as “microbiomes,” consist of microbes “specific to different parts of the body, can persist over long periods of time and can be transferred to other people and to the environment.” Forensic microbiologists examine the microbiomes to: (1) identify individuals after death, (2) determine the condition of the individual’s health before death, (3) determine how and why the person died, (4) the elapsed time postmortem, and (5) from where the individual came.
Rooted in the principle of exchange as formulated in the early 1900s by French criminologist Edmond Locard (“every contact leaves a trace”), microbiology began in the early 2000s with scientists seeking ways to defend against bioterrorism. But in 2021, two researchers (Procopio and Gino), along with their colleagues from the University of Central Lancashire in the U.K. and the University of Eastern Piedmont in Italy, authored a study that “first described the touch microbiome—the unique bacterial populations on individuals’ skin.” These bacteria can be transferred and persist on nonporous surfaces for up to six months in uncontrolled indoor surroundings.
The researchers also analyzed DNA of dead bodies from cold cases that had been frozen for up to 16 years and identified “specific populations of microbes linked to the manner of death and decomposition stage of the bodies.” This demonstrated that microbial signatures may be used to better understand cold cases where DNA extracts remain available.
A third researcher, Magni, studied cotton t-shirts worn by two people for 24 hours in Australia. The t-shirts, along with unworn t-shirts used as controls, were placed in a controlled environment for up to six months. Samples from both the worn and unworn t-shirts were removed at various times and frozen. The frozen samples were then shipped to Italy for microbial DNA extraction, with the DNA sequencing conducted afterward in the U.K. The results “showed the two volunteers transferred distinct and recognizable microbes onto the clothing, each unique to the respective individual.” The researchers also “could distinguish between worn and unworn items even after an extended period of time. The microbiome remained stable on the worn garment for up to 180 days.”
The researchers concluded: “clothing can provide even more evidence. The discovery of unique microbiomes capable of identifying individuals from clothing marks a significant stride forward.”
Source: forensicmag.com
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