Long-loathed as itchy household pests, bed bugs have emerged with a surprising new role. Malaysian scientists have discovered that these blood-sucking insects can become unlikely allies in solving crimes. A team from the Science University of Malaysia (USM) in Penang has found that tropical bed bugs can retain DNA from human prey for up to 45 days, offering a novel method for forensic investigations.
This breakthrough suggests that bed bugs, which typically hide in headboard cracks, mattress seams, and pillow covers, could serve as crucial evidence in identifying suspects at crime scenes. From a mere speck of blood, police investigators might one day reconstruct a full profile of an offender if these critters are present at a crime scene. Entomologist Abdul Hafiz Ab Majid explained that analyzing the insects could reveal a suspect’s gender, eye color, hair, and skin color.
DNA Profiling Potential
In a laboratory at USM’s School of Biological Sciences, Abdul Hafiz and postdoctoral researcher Lim Li have dedicated nearly five years to studying tropical bed bugs. Known scientifically as Cimex hemipterus, these are the most prevalent species in Malaysia and other tropical regions. The bugs are kept in containers wrapped in black plastic to simulate their natural environment.
“We place folded pieces of paper inside the small containers so the bed bugs have something to climb on,” Hafiz said. The lab maintains a temperature of 23°C to 24°C, allowing the insects to consume 1.5 to 5.3 microliters of blood per feeding—an amount less than a droplet, Hafiz explained.
Researchers discovered that DNA extracted from bed bugs that had fed on human blood could recover basic “phenotypic profiling,” including a person’s observable traits and gender, for up to 45 days. By using STR (Short Tandem Repeat) and SNP (Single Nucleotide Polymorphism) markers, researchers can determine the gender, eye, hair, and skin color of potential suspects long after they have left the scene.
“We call bed bugs the ‘musuh dalam selimut’ (Malay for ‘the enemy in the blanket’),” Hafiz said, adding that “they can also be spies” to help solve crimes.
The Perfect Forensic Tool?
Unlike mosquitoes and flies, bed bugs cannot fly and become engorged after feeding, limiting their movement to within 20 feet of their feeding spot. “That’s what makes them unique. We can say they are perfect to use as a forensic tool compared to mosquitoes that… fly away,” Hafiz added. This makes them particularly useful at crime scenes where fluids have been wiped away, as the critters often remain well-hidden.
In the lab, researcher Lim demonstrated a feeding session, even joking about being a “willing victim” for science. “I let them feed on my blood when I wanted to test how long the human DNA would take to degrade,” she said. Lim emphasized that bed bugs are “misunderstood creatures” and do not spread diseases, although their bites can leave an itchy rash lasting for weeks.
“Maybe we can try educating people because the bed bugs are not actually vectors. So even if you get bitten, they can’t transmit diseases to you,” Lim said.
Limitations and Future Prospects
While the researchers envision a future where bed bugs at crime scenes could lead investigators to suspects, Hafiz cautioned that the insects are not a magic fix. Bed bugs have their limitations, particularly in solving cold cases. “It only gives investigators a time frame of 45 days to use bed bugs as evidence—and only if they are available at the crime scene,” he noted.
This development follows a growing interest in unconventional forensic tools, reflecting the innovative spirit of modern scientific research. The study, titled “Human profiling from STR and SNP analysis of tropical bed bug, Cimex hemipterus,” was published in Nature’s Scientific Reports two years ago, marking the first documented forensic use involving tropical bed bugs.
As forensic science continues to evolve, the potential role of bed bugs in crime scene investigations could offer new avenues for solving cases, particularly in regions where these insects are prevalent. The findings from USM highlight the importance of interdisciplinary research and the unexpected ways in which nature can contribute to human knowledge and problem-solving.
