Forensic Biology

Forensic biology applies biological principles and methods to legal and investigative questions. It encompasses body fluid identification, DNA and RNA profiling, trace evidence examination and ecological approaches such as palynology and microbiome analysis. By linking biological materials—blood, saliva, semen, skin cells, pollen and microbial communities—to individuals, events or environments, the discipline supports reconstruction of crime scenes, timing of events and victim–perpetrator associations. Recent years have witnessed the integration of high-throughput molecular assays, portable sequencing platforms and advanced statistical frameworks to enhance sensitivity and specificity. Key advances include multiplex assays for fluid-specific RNA and microRNA markers, metagenomic profiling of environmental and skin microbiota, and automated devices for on-scene DNA extraction and analysis. The global impact of these methods spans criminal justice, mass disaster identification and wildlife crime investigations, with a focus on rapid, robust workflows that preserve evidentiary integrity and withstand rigorous statistical evaluation.

Research from Nature Portfolio

Researchers have demonstrated that microRNA expression patterns can reliably discriminate blood, saliva, semen and vaginal secretions. By quantifying a panel of seven candidate microRNAs and applying a probabilistic discriminant model, forensic scientists achieved over 90 % accuracy in identifying fluid types, even in mixed or aged samples, while accounting for individual and physiological variables. In a separate study, human DNA recovered from indoor air and settled dust was shown to provide an occupancy record in enclosed spaces. Using targeted sampling and a Bayesian statistical model to optimise collection protocols, investigators retrieved identifiable DNA profiles from as many as 12 individuals with minimal sampling. These findings extend the notion of touch DNA to environmental reservoirs and offer new venues for reconstructing presence and movement in indoor crime scenes.

Research from all publishers

A 2024 evaluation of immunochromatographic lateral flow assays showed that portable antibody-based kits can detect blood and semen stains on cotton, denim and leather up to three months after deposition, with field-level sensitivity equivalent to laboratory tests and compatibility with downstream STR profiling. Complementing protein-based screens, mass spectrometry-driven proteomics has expanded fluid identification to include rare matrices and simultaneous species determination, offering a rapid, single-step alternative to conventional cascade testing. In parallel, studies of the forensic microbiome have illuminated the interdependence of body fluid classification and time-since-deposition estimation. High-throughput 16S rRNA sequencing of saliva, semen, vaginal and menstrual blood stains revealed that while microbial succession reduces discrimination over 30 days, fluid-specific community signatures enable fluid identification at all timepoints and support menstrual blood age prediction with low mean absolute error, underscoring the need for sequential fluid type assignment before temporal analysis.

Forensic Biology publication trend

The graph below shows the total number of articles in forensic biology across all publications each year (not limited to Nature Index journals).

Technical terms

microRNA profiling: Measurement of fluid-specific small RNA molecules by RT-qPCR to distinguish body fluids.

Probabilistic discriminant model: A statistical framework that assigns posterior probabilities to candidate fluid types based on marker expression.

Lateral flow assay: A portable immunochromatographic strip test that uses labelled antibodies to confirm the presence of target proteins.

Short tandem repeat (STR) profiling: Amplification and fragment analysis of polymorphic DNA repeat loci for individual identification.

Microbiome-based analysis: Characterisation of microbial community succession in stains to inform fluid type and time-since-deposition.

Bayesian statistical model: A method combining prior information with observed data to optimise sampling strategies and evaluate evidence likelihood.

References

1. Forensic Biology: A Passport for Biological Evidence.
2. Distinct spectrum of microRNA expression in forensically relevant body fluids and probabilistic discriminant approach. Scientific Reports (2019).
3. The invisible witness: air and dust as DNA evidence of human occupancy in indoor premises. Scientific Reports (2023).
4. Assessment of Blood and Semen Detection and DNA Collection from Swabs up to Three Months after Deposition on Five Different Cloth Materials. International Journal of Molecular Sciences (2024).
5. Mass spectrometry-based proteomics as a tool to identify biological matrices in forensic science. International Journal of Legal Medicine (2012).
6. Body fluids should be identified before estimating the time since deposition (TsD) in microbiome-based stain analyses for forensics. Microbiology Spectrum (2024).