Cracking the Code: How Next-Generation Sequencing is Redefining Forensic DNA Analysis.

For decades, forensic DNA analysis has relied heavily on Short Tandem Repeats (STRs), a method that revolutionized criminal justice by enabling accurate human identification. However, as cases have grown more complex—especially involving degraded, mixed, or minimal biological evidence—conventional DNA typing has faced limitations. Enter Next-Generation Sequencing (NGS): a breakthrough in genomic technology that is reshaping the future of forensic science.

Next-Generation Sequencing, also known as massively parallel sequencing (MPS), allows forensic scientists to decode vast regions of the genome at once, offering a far more comprehensive look at DNA than traditional capillary electrophoresis-based methods. This ability to simultaneously analyze thousands of genetic markers enables higher discrimination between individuals, even in cases involving complex mixtures or degraded samples. Unlike traditional STR analysis, which focuses on a limited number of loci, NGS can sequence entire mitochondrial genomes, autosomal STRs, Y-STRs, and single nucleotide polymorphisms (SNPs) in a single run.

One of the most groundbreaking advantages of NGS is its power in forensic phenotyping—the ability to predict physical characteristics such as eye color, hair color, skin tone, and even biogeographic ancestry from DNA. This is especially valuable in cases with no known suspect, providing investigative leads when other evidence is scarce. Tools like HIrisPlex-S and Snapshot DNA Phenotyping have already been used in real-world cases to produce composite sketches directly from unidentified DNA, giving law enforcement an entirely new way to visualize potential suspects.

Additionally, mitochondrial DNA (mtDNA) sequencing through NGS is proving especially useful in analyzing highly degraded samples, such as those recovered from cold cases or mass disasters. Because mitochondrial DNA is more abundant and resistant to degradation, whole mtDNA sequencing can reveal maternal lineage with high precision. Similarly, Y-chromosome analysis is being expanded through NGS to improve discrimination between male contributors in sexual assault cases.

Recent advancements have also focused on the integration of NGS with forensic microbiology. By analyzing microbial DNA at crime scenes or on personal objects, forensic scientists can now estimate postmortem intervals, identify the geographic origin of evidence, or even trace contact between individuals through shared microbial signatures. These developments are turning NGS into a multidisciplinary tool that extends far beyond human identification.

Despite its promise, the implementation of NGS in routine forensic casework still faces challenges. High costs, complex data interpretation, and a need for standardization across laboratories remain key hurdles. However, collaborative efforts—such as those by the International Society for Forensic Genetics (ISFG) and national forensic science agencies—are working to create guidelines, training, and validation protocols to make NGS more accessible and legally defensible.

The U.S. Federal Bureau of Investigation (FBI) and organizations like the National Institute of Standards and Technology (NIST) are already investing in integrating NGS into CODIS (Combined DNA Index System), envisioning a future where forensic databases include more comprehensive genomic profiles. Once fully operational, NGS has the potential to drastically increase the power and reach of forensic databases worldwide.

In conclusion, Next-Generation Sequencing represents a quantum leap in forensic DNA technology. It provides deeper insights, greater accuracy, and expanded capabilities that were previously impossible using traditional methods. As laboratories adapt to this transformative technology, forensic scientists will be better equipped to solve complex cases, identify unknown individuals, and ultimately bring justice with even greater scientific confidence.

MS. SHIVANGI PARMAR
Asst. Professor,
Department of Forensic Science
Parul University