Mycology: Missing Weapon In Forensic Arsenals?
If anyone bothered to look, crime-solving clues can often be found in fungi.
In 2002, two 10-year-old British schoolgirls vanished shortly after being seen walking near their homes in Soham early one evening. Their bodies were found 13 days later 17 miles from the village, in the woods near Lakenheath, Suffolk.
Among the forensic specialists called in by police was Patricia Wiltshire, one of the UK’s foremost experts in ecology, botany, and mycology. Wiltshire examined the foliage around the ditch where the bodies had been concealed. Although the growth appeared untouched, she noticed an area where stinging nettles had sprouted new sideshoots. Since sideshoots grow only when the nettle has been trampled or damaged, this indicated the point where the bodies had likely entered the ditch. Plus, from the rate of growth of the shoots,Wiltshire established that the nettles had been broken 13 days earlier, providing the police with an indication of when the crime occurred.
Mycology, or the study of fungi, comes in here. Wiltshire then analyzed soil samples taken from the suspect’s vehicle and from the crime scene. In both samples she found spores of a fungi species known to be common on dead nettles, thus providing a link between the suspect and the location where the bodies were found.
The Lakenheath murders provide a clue to the forensic potential found in fungi. Recent research has shown how forensic mycology can aid investigators by connecting a victim and suspect, determining a location, helping define cause of death, deducing interval since death, and discovering whether a body has been moved. The presence of mushroom genuses Amanita and Psilocybe can indicate the involvement of hallucinogenic drugs.
“If fungi could be shown to grow predictably for a given environment as insects are, it could be useful for determining the post-mortem interval,” said Kelly Elkins, director of the Forensic Science Department at Metropolitan State College of Denver. Entomology has long been employed to discover post-mortem interval, much of it based on research carried out at the Body Farm at the University of Tennessee’s famed Forensic Anthropology Center. In order to establish mycology as a forensic tool, systematic experimental testing of specific fungi under specific conditions need to be carried out to predict outcomes. No one appears to be doing this, however.
“No one here is doing anything [with forensic mycology] and we do not know anyone who is,” said Richard Jantz, the Center’s director. Jantz did not dismiss the forensic potential of mycology. “We would welcome the research,” he said.
Time-since-death research seems a good place to start. Fungi found growing on or in corpses are not the same species that colonize living tissue, yet information on what role particular fungal species play in the decomposition of human remains is almost nonexistent.
While forensic mycology has yet to gain traction in the United States, it has been used in a few cases in the UK. Aside from the Lakenheath murders,Wiltshire, a forensic ecologist and botanist at the University of Aberdeen, has worked on more than 200 cases. Still, few mycological protocols are established to aid the forensic investigator, and legal precedents to guide judicial and evidentiary decisions are equally rare. Even in the UK, until recently the appearance of mycology in forensic investigations was largely restricted to cases involving poisonous or psychotropic species, where “magic” mushroom species are involved.
“The principal reason for the absence of mycological protocols is a lack of awareness amongst crime scene investigators that fungi have the potential to make significant investigative contributions,” said David Hawksworth, of the Plant Biology department at the Universidad Complutense de Madrid and the Department of Biology at the Natural History Museum, London.
This lack of awareness may begin to change following a recent landmark paper authored by Hawksworth and Wiltshire, who happen to be married to each other. The paper (Hawksworth DL,Wiltshire PE, “Forensic mycology: the use of fungi in criminal investigations,” Forensic Sci Int. 2010 Jul 13. [Epub ahead of print]) is the first overview of forensic mycology to appear in the literature.
Hawksworth describes in detail how fungal spores, like traces of plant material, can be extracted from footwear or clothing during investigations. Unlike other organic evidence, however, fungi can also grow on stone, brick, tile, pavement, wood, leather, plastic, and rubber, thus potentially providing trace evidence in almost any environment.
“Although there do not appear to be any cases reported in the literature of fungi having been used as trace evidence in criminal cases, in the past three years we have successfully used them in our own forensic casework and they have greatly augmented palynological data,”Hawksworth said. Palynology is the study of pollen, plant spores, and other microscopic entities.
Indeed, the fields of botany,palynology, and ecology encompass aspects of mycology. Wiltshire maintains that mycology greatly enhances the resolution of palynology. Together, both macroscopic and microscopic fungi can give the investigating officers information hitherto unavailable to them. This information includes time since death, time since deposition, and evidence of body disturbance.
“Both botany and mycology can provide intelligence and evidence at crime scenes, in the mortuary, and in analysis of exhibits,” Wiltshire said.
Since combining Hawkworth’s expertise with her own, she said the team has achieved impressive characterization of soils, other deposits, and vegetation.
“We’ve been able to match crime scenes to items retrieved from suspects, such that contact of the item with the place has been convincingly demonstrated many times,” she said.
Hawksworth and Wiltshire, for instance, have found that methods of sampling vegetation, soils, and microscopic exhibits of plant and animal structures can yield evidence of fungal species that are extraordinarily rare. In one case, the team encountered the distinctive spores of Caryospora callicarpa, although no specimen of the fungus itself has been collected in the UK for 150 years.
“Occurrences of such rare species make them especially valuable as trace evidence,” Hawksworth said.
Fungi are not obvious clues. It takes a sharp investigative eye to see what is often invisible. Hawksworth said in several cases in which he and Wiltshire have been involved it was the astuteness of investigators in recognizing fungal growth present on human remains or artifacts that led to the pair being called in.
Who You Gonna Call
Even if forensic investigators suspect a fungal link, there is a shortage of forensic mycologists available to respond—another reason for the slow growth of forensic mycology. Hawksworth estimates there are no more than eight fungal specialists working full time in the UK, and there is no quick-fix on the horizon. It takes a Ph.D. and years of field experience to finally produce a fully competent professional mycologist. A Google search of “forensic mycologist” currently returns no hits.
“It’s important to remember that our skills cannot be learned quickly or by doing a course at college,”Wiltshire said. “It’s relatively easy to apply forensic protocols to casework, but to achieve the knowledge and experience necessary for competent interpretation of our data, a great deal of personal experience of organisms, habitats, and whole ecosystems is necessary.”
It’s not hard to see why it takes so long to master mycology. Some 100,000 species of fungi are known world-wide. Hawksworth says approximately 800 new species are being added every year. He estimates there may be around 1.5 million fungal species in existence. Something like 50 to 100 different species of fungi can be isolated in any single soil sample.
Douglas Page writes about forensic science and medicine from Pine Mountain, California. He can be reached at firstname.lastname@example.org.