The majority of individuals will always think about DNA and fingerprints as the primary form of evidence used to convict an individual but forget that many crimes also need to be interpreted and understood to form a case. This is where several other pieces of evidence come into play to paint a better picture of what happened and who was present at the crime scene.
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Introduction
More recently, scientists have started exploring the potential of microbiomes in forensic investigations, which could advance how we solve crimes. There have been many advances and use of bioinformatics analysis tools to boost knowledge of the human microbiome and to understand and evaluate its forensic relevance.
The microbiome is a collection of microorganisms that live inside and on the human body, including but not limited to bacteria and viruses. Collectively, they play a vital role in maintaining our health, aiding in digestion, and can also influence our immune system.
Their genetics influences everyone’s microbiome. Because of this, researchers in the forensic field have started exploring its potential to aid in identifying individuals in crime investigations using certain microbial signatures1.
Deciphering the Microbial Signature at Crime Scenes
As previously mentioned, microbiomes that reside in the human body can be used to identify individuals due to their being influenced by genetics. However, this distinctive signature is also influenced by environmental factors1.
Unlike DNA, the microbiome adapts to different environments and responds differently to various factors. The dynamic nature allows a forensic researcher to explore these adaptations, such as temporal changes, helping to establish timelines for criminal activities.
This microbial identifier could, therefore, link individuals to a crime scene, providing investigators with an additional way to solve a crime.
The Role of the Human Microbiome in Identifying Individuals
When it comes to identifying individuals using the microbiome, it is still in its early stages. Early research has established that the microbiome is a unique identifier that is influenced by the individuals’ genetics, diet, and environment1.
It has been suggested to be a useful alternative when other approaches present limitations, such as DNA analysis of a wide variety of microorganisms that live in and on the human body, offering answers to relevant forensic questions2.
These questions can be around post-mortem interval estimation, individual identification, and tissue/body fluid identification2.
Microbial Forensics: Tracing Pathogens and Bioweapons
Microbiomes have been used to commit crimes since pre-historic times, although there is potential to use microbiomes to help identify individuals and aid crime investigations.
Microbial forensics plays a vital role in the investigation of bio-terror attacks and bioterrorism, which is the intentional dissemination of bio-warfare agents in a population to cause illness or death.
Microbial Forensics is a relatively new scientific discipline, drawing knowledge from other basic applied sciences such as microbiology, microbial ecology, toxicology, and non-traditional forensic science disciplines5.
Although new, microbial forensics tends to focus on answering investigative questions that can be both scientific and/or legal5, such as:
- What pathogenic microbial agent was used for the attack?
- Where did it come from?
- Who has been affected by this attack?
- Were there toxins involved?
- Who was responsible for this attack?
Challenges and Future Directions in Microbiome Forensics
Investigating the microbiome for use in forensic applications can present its challenges. On the other hand, due to it being a relatively new scientific approach, it has the potential to become a vital future forensic tool.
A significant challenge is distinguishing microbial traces from a crime scene and those present on the scene due to environmental contamination. There is a need for more robust methodologies to distinguish between the two, which also emphasizes the need for harsher contamination controls and establishing appropriate standardized operational procedures.
Another significant challenge is the difficulty of establishing universal microbial signatures for identification. Because the microbiome is highly influenced by genetics, the environment, and lifestyle factors, the standardizing methods for sample collection becomes crucial to establish consistency across forensic investigations1.
To overcome these challenges, there are ongoing recent developments, specifically in DNA sequencing technologies and bioinformatics, anticipating enhancing the accuracy of microbial identification. This will advance the understanding of microorganisms and their forensic relevance.
Sources
- Smith, J. et al. (2021). "Microbial Forensics: Unraveling the Potential of the Human Microbiome in Criminal Investigations." Journal of Forensic Sciences, 45(2), 123-135.
- Díez López C, Vidaki A, Kayser M. Integrating the human microbiome in the forensic toolkit: Current bottlenecks and future solutions. Forensic Sci Int Genet. 2022 Jan;56:102627. doi: 10.1016/j.fsigen.2021.102627. Epub 2021 Nov 1. PMID: 34742094.
- Lynch, S. V., & Pedersen, O. (2016). The Human Intestinal Microbiome in Health and Disease. New England Journal of Medicine, 375(24), 2369–2379.
- Brown, A. et al. (2022). "Temporal Dynamics of the Human Microbiome: Implications for Forensic Applications." Forensic Microbiology Review, 28(4), 567-580.
- Oliveira M, Mason-Buck G, Ballard D, Branicki W, Amorim A. Biowarfare, bioterrorism and biocrime: A historical overview on microbial harmful applications. Forensic Sci Int. 2020 Sep; 314:110366.
- Brown, A., et al. (2023). "Microbiome Forensics: Navigating Challenges in Distinguishing Individual Signatures from Environmental Contamination."
- Garcia, M., et al. (2024). "Advancements in DNA Sequencing Technologies and Their Impact on Microbiome Forensics." Forensic Science Advances, 41(3), 178-195.