Imagine you’re a detective working on a murder case. You have a body, but you believe it was moved from another location. Now what? There’s one unexpected tool you might use to follow up on this suspicion: forensic palynology. That’s the application of palynology – the study of pollen – to crime investigation.
But how does pollen have any bearing on forensics? While usually unseen, pollen is essentially ubiquitous in terrestrial habitats, and it is extremely tough. In fact, pollen is so durable that paleontologists can examine fossilized pollen grains in ancient sediments to see what plants grew during prehistoric times. And the “signature” of which pollen grains are present is specific to a particular place (because different plant species occur in different areas) and time (because different plant species flower at different times).
All of that makes pollen an ideal biomarker for linking people and objects to particular places and times, a central need in forensic investigations. Despite this potential utility, forensic palynology has been underutilized, because of its reliance on specialized experts to meticulously identify pollen visually under the microscope.
But researchers have recently developed a new technique for identifying pollen, using genetics. Since it makes identification much easier and faster for large numbers of pollen samples, we believe this development has the potential to transform forensic palynology, allowing us to harness the power of pollen to solve crimes.
Pollen as private eye
Forensic palynology has been particularly useful in cases where there is suspected movement of evidence, or where a crime has occurred in a location with distinct plant species. For example, following the Bosnian war, investigators uncovered mass graves where bodies had been moved from different locations. Pollen was one of the lines of evidence used to trace bodies to their original burial sites. In a case in New Zealand, a burglar was tracked to the scene of the crime when pollen grains on his clothing were matched to an uncommon plant species growing in front of the victim’s house.