Biology

Forensic Botany: Catching Killers with Plants

By Katie Bean

Solving crimes is an intricate and befuddling process, where often the most minute details can provide ground-breaking evidence to bring justice. An ever more fundamental component in the field of forensic science is forensic botany – the utilisation of plants in crime investigations. The examination of spores, leaves and various other plant parts can help identify where and when a particular crime may have occurred. (Avis-Riordan 2020) Forensic botany itself has been accepted in courtrooms for 75 years as solid evidence and can help to determine what has happened to a dead body, for example, due to the momentous impact such an event would have on the local ecology. In this article, I aim to explore how forensic botany is used in such cases and why it is so reliable and beneficial.

Even the most perfect of crimes leave behind traces or at least a disruption in the environment. If a criminal moves from one place to another, this can be detected by the ‘hooks or barbs’ of a particular seed or other plant component that could be abundant in one area, for example, but scarce in another. Morbid this may be, but evidence can also be left behind in the contents of a dead person’s digestive system, where a certain food or pollen type can help scientists to determine the location of a crime. (Graham, n.d.) What is more, certain poisons can be identified if they contain a plant-based toxin, allowing investigators to obtain more information concerning the nature of the crime. (Avis-Riordan 2020)

Furthermore, plants can be used as an indicator for forensic botanists at a crime scene, revealing whether a person has been buried in a certain area. As mentioned before, the decay of a body causes many significant changes in the neighbouring ecosystem, often creating a so-called ‘necrobiome’ (the collection of organisms that feast on a decaying corpse) (Yong 2015). For example, the decomposition of a human can release around 2.6 kilograms of ‘nitrogenous compounds’ into the environment, which in turn, causes a surge in chlorophyll levels of nearby plant species. An incredibly green area of vegetation among an area of less green vegetation, therefore, would be very suspicious to a forensic botanist.

Figure 1. Forensic Botany [https://wp.stu.ca/forensicscience/forensic-botany/]

If it is a deceased smoker you are looking for, however, a fundamental clue in the investigation is due to increased cadmium levels in their body. The disruption to the molecular structure of photosystem II in plants because of the presence of this substance can cause certain changes to the light absorption and reflection rates, therefore affecting the colour of plant leaves.(The Economist 2020) Therefore, forensic botany can give host to a wide range of major details. The reason for this is because of the consistency in decomposition: it will always occur in the same manner, only varying as a result of temperature. It is inevitable, therefore, that the same type of chemicals will be released into the surrounding environment – this allows solid evidence to be relied upon in court cases. (Inverse 2020)

An example of a court case that forensic botany has been crucial in was the Cher Elder case. Elder, a 20-year-old, was killed in 1993 by Thomas Luther. It was exceedingly hard to prove that Luther was in fact the murderer around that time in until the authorities received information in 1995, from Cher’s ex-boyfriend that her ‘grave’ was situated in an exact location in the west of Denver, Colorado. A forensic botanist working on the case, Victoria Trammel, examined the roots of the plants around the grave. Herbochronology allowed her to determine that the roots, and therefore the grave, was about two years old, thus proving that Luther was active at that time. He was convicted in 1996 on account of second-degree murder. (Bock and Norris 2016, 85-94)

Forensic botany is one intrinsic part of a whole myriad of fields within the discipline of forensics; entomology, pathology and palynology can all provide such hardcore evidence in legal cases. Moving forward, advances in technology can improve the analysis of DNA as well as analysis of the microbiome. (New Scientist 2017) Advanced microscopy will also undoubtedly allow forensic botanists to look at plants in more detail and consequently solve crimes more efficiently. (ATA Scientific 2020) Hopefully, this will make the world of crime investigation become less befuddling to scientists!

Bibliography

ATA Scientific. 2020. “13 TECHNOLOGIES FOR MODERN FORENSIC SCIENCES ATA scientific. https://www.atascientific.com.au/technologies-forensic-sciences/.

Avis-Riordan, Katie. 2020. “Plant forensics: Cracking criminal cases.” https://www.kew.org/read-and-watch/how-forensic-botany-plant-science-solve-crimes.

Bock, Jane H., and David O. Norris. 2016. “Chapter 5 – Cases Using Evidence from Plant Anatomy.” In Forensic Plant Science, 85-94. https://www.sciencedirect.com/science/article/pii/B9780128014752000051?via%3Dihub.

Chadwick, Jonathan. 2020. “Caught in the Long Grass.” Laboratory News. https://www.labnews.co.uk/article/2030360/caught-in-the-long-grass.

The Economist. 2020. “Finding bodies in forests.” https://www.economist.com/science-and-technology/2020/09/03/finding-bodies-in-forests.

Graham, Dr Shirley. n.d. “Interesting Jobs – Crime Scene Botanicals – Forensic Botany.” Accessed November 22nd, 2020. https://www.botany.org/PlantTalkingPoints/Crime.php.

Inverse. 2020. “FORENSIC BOTANISTS: THE SCIENCE OF USING PLANTS TO FIND BODIES.” Inverse. https://www.inverse.com/science/forensic-botanists.

New Scientist. 2017. “Future forensics: Harnessing the spirit of Sherlock Holmes.” New Scientist. https://www.newscientist.com/article/2130786-future-forensics-harnessing-the-spirit-of-sherlock-holmes/.

Yong, Ed. 2015. “Meet the Necrobiome: The Waves of Microbes That Will Eat Your Corpse.” The Atlantic. https://www.theatlantic.com/science/archive/2015/12/meet-the-necrobiome-the-predictable-microbes-that-will-eat-your-dying-corpse/419676/.

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