Sunday, September 21, 2014

Forensic Botany--Investigating Crime with Dr. Jane Bock

Dr. Jane Bock
Dr. Jane Bock
Some botanists retire to garden, some retire to travel…Dr. Jane Bock retired to investigate crimes.  

She is a forensic botanist, one of a small group of experts who use their a knowledge of plants to help solve crimes. 

How can plants reveal the truth? It turns out there are many ways. 

Jane got involved when an M.D. who worked as an assistant coroner called her for help. At the time she was a Professor of biology at the University of Colorado in Boulder, specializing on plant biology, from after-fire dynamics in Rocky Mountain forests to studies of Arizona desert grasslands to studies of high alpine plants in Eurasia, teaching everything from introductory botany to graduate seminars, while filling major service roles at the University. (In 1997 she received the Hazel Barnes Prize, largest and most prestigious single faculty award funded by the University of Colorado, Boulder). She thought the idea of crime investigation, well, icky. Crimes, deaths, blood. She said part of what she always liked about plants is that they aren’t bloody.

But the doctor told her the story, of a young woman with a quiet and industrious life as a summer intern who was stabbed to death. The investigators wanted to know whether her stomach contents could reveal anything about where she had been. And Jane was hooked. She was and is passionate about justice, so, although she never had thought about contributing to the US justice system, she listened. One by one her objections were met: what can you tell from a last meal? Quite a bit. Many plants have distinctive features so seeds or bits of skin will reveal an olive or an onion. Second, Jane wouldn’t have to work with blood and guts, the coroner’s office had neatly mounted the material on laboratory slides: it would be like a classroom study.

olive as seen through a microscope
olive as seen through a microscope

onion as seen through a microscope
onion as seen through a microscope
Jane agreed to look at the slides, and documented a last meal with red cabbage, beans and onion. Since the victim’s lunch at work had not included any of those, it seemed likely she had met someone for dinner. Presumably someone unexpected but someone she knew.

About the same time a serial killer confessed to a string of killings across the country, of women who looked similar to this girl. 

The prosecutors were able to connect the dots: she had met him by chance at her brother’s house, where he had been using the phone to call about car problems. He made an effort to be charming and she didn’t realize that he was a stranger to her brother. After that he stalked her, until the day he walked up to her at the bus station: “Remember me? We met at your brother’s house...”.

The botanical evidence was an important piece in reconstructing the victim’s day.

Since then, botanical questions involving forensics have repeatedly been sent to Jane. She is selective: in many situations botanical study won’t help. But in others, it can be very informative.

Plants easily reveal that the last meal included something the victim didn’t pack in their bag lunch or was at a Mexican or Chinese restaurant. For example compare the seeds bel0w:
poppy seed
scanning electronmicrograph of poppy seed
strawberry seed
scanning electron micrograph of strawberry seed
Stomach contents are not the only type of useful evidence provided by plants. They can also help determine time or place. Jane works partly with slides or little plastic bags of evidence collected by the police to determine what the plants are that are on the slide or in the evidence bag.  More than that, she can infer times and places or eliminate alternatives from her knowledge of where such plants are found and when they flower or set seed. If the victim’s socks were stuck full of seeds such as cheatgrass (Bromus techtorum) which release in mid summer, the death was much more likely in mid summer than December or April. In a real case Jane investigated, the truck’s owner denied going up into the mountains where the body was found, but there were bits of plants in and on  the pickup that are only found in upper elevation forests. Added to other discrepancies in the man’s testimony, he was found guilty of the murder of his wife.

Two places with quite different plants:

plants in residential neighborhood
plants in residential neighborhood, Colorado, 5000'
fields, 5000', Colorado
plants in uncultivated fields, Colorado, 5000'
Evidence bag of plants from the suspect's home
Evidence bag of plants from the suspect's home 
Evidence bag of plants from the crime scene
Evidence bag of plants from the crime scene 

Jane also goes to rural areas with a team to look for the patterns of the plants that might reveal unmarked graves. When a grave is dug, the plants are disturbed and it takes several years before the plant community fills in and once again looks the way it did before the disturbance. Whether or not such crimes can be solved, finding unmarked graves can bring closure to the distraught families of missing persons. 

Just as botanists watch movies and say “that wasn’t filmed in New York, those rhododendrons are from the Carolinas” (Last of the Mohicans), plants provide a lot of information to the trained eye. 

From a legal point of view, sometimes the plant information is inconclusive, sometimes it exonerates the suspect, sometimes it helps get a confession or conviction. Jane had many more fascinating stories where plants were part of the evidence.

Jane Bock didn’t expect to become a forensic botanist, but it is a wonderful fit between her botanical knowledge and her belief in justice. She emphasized to me that much more could be done in the legal system using plants as forensic evidence. More botanically trained investigators are needed!

Finally, here’s a plant-puzzle for you:  If the suspect’s hiking boots included a bit of cattail (Typha, called reedmace in England) and a reed seed (Phragmites), will you believe that, for weeks, she has not worn the boots except in the city?

cattails in marsh
cattails in marsh

Comments and corrections welcome.

Further reading:
Interview with a Forensic Botanist: Dr. Jane Bock.

Bock, J. H. 2013. The use of macroscopic plant remains in forensic science. IN Elias, S.A. editor, The Encyclopedia of Quarternary Sciences. Vol. 4 pp. 542-547. Amsterdam: Elsevier.

Kathy Keeler

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