The Forensic Toolbox: DNA, Microbes, and Insects Help Decode a Crime Scene

Crime documentaries and courtroom dramas offer only a glimpse into the complex world of forensic science. While DNA analysis plays a key role in identifying suspects or victims, the scope of investigation can go beyond that with the help of creepy-crawlies, both big and small. Researchers also study insects and microbes on decomposing bodies, using them to uncover the time of death. These microscopic clues create valuable patterns, helping investigators narrow down the timeline and opening new avenues for solving cases.

From Footprints to Fingerprints: Forensics in the Making

DNA profiling has become a powerful tool in solving crimes, tracing killers, and uncovering mysteries, from historical investigations to modern criminal cases. By analyzing genetic markers, forensic scientists can now pinpoint individuals with remarkable accuracy. The technique helped identify suspects and solved cold cases and verified royal lineages. Not only that, but environmental sampling gives investigators a bigger picture on DNA traces left behind. “There's a lot more nuances with DNA testing than people appreciate,” said John Butler, a forensic scientist at the National Institute of Standards and Technology. Explore how DNA profiling continues to impact forensic science in tracking down killers and solving complex cases.

Discover more about the applications of DNA in this feature.

Using Creepy Crawlies for Crime Scenes

When entomologist and micromoth expert Sibyl Bucheli received an unexpected call, she never imagined it would lead to a crime scene—or a human scalp arriving at her office. Examining it, she discovered that case-making clothes moth caterpillars had woven the victim’s hair into their silk shelters, allowing her team to extract mitochondrial DNA. Now, she collaborates with the Southeast Texas Applied Forensic Science Facility studying how insect and microbial communities shape the process of decomposition from body donations. Rather than capturing a single moment in time, these bodily investigations offer valuable insights into the ongoing patterns of human decomposition.

Venture into the macabre realm of moths and microbes alongside human decomposition.

Justice in the Details: One Scientist’s Forensic Calling

Inspired by The New Detectives, Colby Duncan’s journey from aspiring lawyer pivoted to forensic science at the beginning of her undergraduate studies. By blending her love for justice with biology, she was excited to solve forensic puzzles. “I wanted to help people in the best way I could. I wanted a job where every day was something different,” explained Duncan. “That naturally led me into forensics.” However, before tackling the thousands of cases her crime lab processes each year, she underwent intensive training—honing both scientific precision and courtroom presentation skills. For Duncan, it’s more than a career; it’s a mission to bring answers to families and help justice prevail.

Learn more about her perspective here.

Solving Death’s Timeline with Microbial Timekeepers

Scientists are using microbes to help solve the mystery of time elapsed since death by tracking microbial communities on decomposing bodies in various environments, ranging from blistering heat to freezing cold. Researchers found consistent microbial changes across different locations in the United States. Notably, these microbes matched species found in creepy crawlies. “If you're a microbe looking to decay flesh, riding along on insects that lay their eggs on decaying flesh is probably a pretty good plan,” said Jessica Metcalf, a microbiologist at Colorado State University who studies the microbial world of decomposing bodies. Her findings suggest that microbial patterns could predict postmortem intervals and serve as a reliable forensic tool.

Keep reading to learn more about the microbial “clock” here.

Bridging Faith and Forensics for a Nun’s Sainthood

Sainthood is a lifelong journey, granted by the Pope to those recognized for their virtue and holiness. Sister Marija Krucifiksa Kozulić, a Croatian nun devoted her life to aiding disadvantaged children, lived a deeply spiritual life. Nearly a century after her death, efforts to grant her sainthood began. The first challenge was locating her grave, followed by the need to identify her remains. Forensic scientist Mitchell Holland of Pennsylvania State University was part of an international team of Croatian and American scientists who used DNA analysis to confirm her identity. This meticulous process, which took nearly a decade, marked a significant intersection of science and religion in the canonization process.

Dig deeper into the full story.

Cutting Through the Clutter for Improved DNA Profiling Accuracy

Forensic DNA profiling relies on amplifying short tandem repeats via polymerase chain reaction (PCR). However, during PCR, DNA polymerases can slip on these repeats, producing "stutter" artifacts—fragments one repeat shorter than the true peak. This creates challenges in data interpretation, especially in DNA samples with multiple contributors. “When we started our project a few years ago, we didn’t think it was possible to do it, because many people have tried this before and have not succeeded,” said Bob McLaren, a biochemist at Promega Corporation. Now, McLaren and his colleagues have developed a novel DNA polymerase that significantly reduces stutter formation.

Learn more about this breakthrough here.