As one of the simplest plants on the planet, it's easy to see why moss may be overlooked in favour of weirder-looking flora. But in a new study, a team of researchers has revealed the hidden importance of this unassuming-looking plant – as well as how it helped solve a homicide investigation.
Mosses are a type of bryophyte, along with liverworts and hornworts. As a group, they resemble some of the first land plants on Earth, which appeared around 500 million years ago.
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Although mosses are biologically simple, they are very sensitive and certain species only thrive in specific conditions and habitats.
"Because they’re so small, they have all sorts of microhabitats – even if an area overall seems to be one sort of habitat, they can find a spot that works for them in the shade, or in the canopy, or even growing under the grasses,” explains Matt von Konrat, head of botanical collections at the Field Museum in Chicago, USA, who led the team.
“And different types of even smaller organisms can live on those mosses.”
In 2024, Jenna Merkel, a master’s degree student at George Washington University, USA, began an internship with von Konrat, with the team deciding to write a review of how bryophytes have been used in forensics.
With their results now published in the journal Forensic Sciences Research, the team examined 150 years of scientific literature to see how often mosses appeared in criminal investigations.
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Forensic botany
The earliest case the team found dated back to 1929 in Tyrol, Austria. It was used for a post-mortem interval, where investigators used moss growth on a decomposing skeleton to estimate how long the individual had been dead.
The scientists found a further 10 cases across the USA, China, Finland, Sweden and Italy where bryophytes contained clues that helped answer a crime’s timing, location or circumstance.
Using moss in this way is an example of forensic botany: when plants are used in forensic investigations.
The team’s research also shed light on the famous Lindbergh kidnapping case in 1932, when the son of world-famous aviator Charles Lindbergh was taken from his nursery, with ransom notes soon following.
Wood evidence was presented and accepted in the case hearing in relation to the handmade ladder used to access the nursery window.
An expert from the Forest Service, United States Department of Agriculture, was called in to examine the specific types of wood in the ladder. Evidence later presented in court showed that the wood used to build the ladder matched wood used as flooring in the suspect’s attic.
Modern cases
The team’s paper also details an abduction and homicide case von Konrat and several others worked on.
In 2011, a baby girl was killed by her father but her body wasn’t immediately located. The father only provided scant details of where he had buried her in northern Michigan.
Investigators had discovered microscopic plant fragments on his shoes, so von Konrat led a team of botanists and volunteers to survey the region, cataloguing grasses, trees and mosses in the hope that some of them matched the fragments.
As multiple bryophyte species were left on the shoes, the team had to pinpoint a precise area where all of the species were found.
Using this method meant that the team narrowed the search from seven counties to an area of roughly 50 square feet, with the location later confirmed in a police interview. In this case, the moss species acted in a similar way to the way a fingerprint does.
The researchers hope that their findings will encourage a greater use of bryophytes as forensic evidence in criminal investigations.
“Plants, and specifically bryophytes, represent an overlooked yet powerful source of forensic evidence that can help investigators link people, places, and events,” says Merkel.
Top image: Matt von Konrat, from the Field Museum, examining dried moss collected in 2013 as part of a botanical survey for a homicide investigation
