Plants as crime-solvers

If James Bond were a forensic botanist, he wouldn’t need fancy gadgets to run down the bad guys. He would inspect a crime scene for tiny plant fibers and pollen dust and even analyze the partially digested contents of a victim’s stomach.

Unfortunately, says Missouri plant scientist Shirley Graham, specialists in the field are not always called upon in civil and criminal matters to help investigators who may be ignorant of plants’ potential as evidence and who thus fail to collect evidence properly. The problem is compounded by the expense of certain biochemical tests involving plant DNA and by a lack of laboratories qualified to do the work.

“One good thing is that [the evidence] is often visible and easy for jurors to understand,” she says. “One drawback is that it has not been used sufficiently to have developed the important standardized or statistical background now being demanded of molecular data.”

That means that today’s James Bond has to be technologically up to date to be able to cope with this valuable source of information.

It is not only in criminal cases that plant evidence is useful. Mrs. Graham’s husband, Alan Graham, a pollen specialist, was one of 13 scientists asked to help the defense in a civil case over whether a design flaw in a private aircraft engine’s gas lines had been the cause of a 1989 crash in New Mexico.

Long after the wreckage had lain in a field, plaintiffs charged that the design had made possible an accumulation of biological material — a plug of bee pollen — in the engines’ gas lines. As Mr. Graham recalls, however, he and others testified that the material was similar in origin to that in the field and, anyway, no organic substance could have withstood engine temperatures while the plane was aloft.

Palynology, a subset of forensic botany, is an interdisciplinary science concerned with fossil spores living and dead, pollen grains and similar plant structures. Forensic palynology refers to the use of pollen and spore evidence in legal cases.

The plane-crash case was one of several dramatic stories featured on a panel that, until recently, hung in the U.S. Botanic Garden with the title “Plants in Crime: CSI Botany.” Mrs. Graham regaled a Botanic Garden audience at a March lecture she gave on the subject with several tales illustrating the history and capabilities of forensic plant science.

One of the most significant examples —which helped validate the use of botanical evidence in criminal courts — took place in 1935 during the trial of Bruno Richard Hauptmann, who was charged with kidnapping the son of Charles and Anne Lindbergh.

An expert on wood anatomy and identification was called on to identify the structure of the wood ladder used by the kidnapper, including the kind of wood and even its likely mill source. One of the expert’s tools was the fact that patterns of annual rings in trees, and boards cut from them, are unique, just like the DNA used for identification purposes in humans.

The expert could show that a board from the kidnapper’s attic, which had been cut away, matched the ladder rail found at the scene. Mrs. Graham illustrated how such skills are current by mentioning an episode from a February TV show that had a forensic anthropologist identifying the kind and origin of pollen found in a suspected killer’s ear wax. The grass species associated with the pollen grows only in South Africa, thus providing a clue to the suspect’s travels.

Pollen and spore coverings are slow to decay and can be retrieved from rocks millions of years old. “Because they are microscopic, they remain unseen, silent witnesses, and even if they were visible, unlike fingerprints, they would be nearly impossible to eliminate from a crime scene,” she told her lecture audience. Seeds and fruits are like pollen and have “specialized features, especially if they are provided with hooks or barbs.” These structures are part of their defensive mechanisms.

This knowledge was especially valuable when Mrs. Graham was asked by an Ohio sheriff’s department in 1997 to help with identification of some seed material that was used as evidence in the conviction of a murderer. The botanical trace evidence in this case was material that is not easily or ever digested and often is present “in partially digested stomach contents or excreted in feces.” A careful analysis of the remains can help determine a victim’s last meal and give a clue to the setting or timing of death.

The profession has had a relatively low profile in spite of its proven capabilities. As evidence of this point, Mrs. Graham made note in her lecture of the FBI’s 2003 Handbook of Forensic Services, which she said “mentions the usefulness of wood and cotton fibers and explains how these should be submitted for examination but refers to no other kind of supporting plant evidence.”

The Grahams, retired Kent State University professors who are research scientists and curators at the Missouri Botanic Garden in St. Louis, are among just several hundred palynologists in the United States, according to Vaughn Bryant, director of the Palynology Laboratory in the Department of Anthropology at Texas A&M; University. New Zealand and Australia are far ahead of this country in applying the principles of the science, he says.

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