The Use of Forensic Palynology in Solving Crimes

By Marzia KhanReviewed by Lily Ramsey, LLM

Trace evidence analysis is a significant component of modern forensic investigation and involves analyzing DNA or fingerprints left at a crime scene.¹ When biological evidence is absent at a crime scene, trace evidence may be the only evidence available to fill in the blanks.^1,2

Palynology, the study of pollen and spores, is utilized in forensic science to examine evidence linked to crime scenes. First applied over half a century ago, it remains relatively underutilized in many parts of the world.

Image Credit: Igor Klyakhin/Shutterstock.com

The Power of Pollen and Spores

Pollen and spores are effective forensic tools due to their ubiquity in the environment, which can be advantageous when investigating a crime.⁴

Several types of pollen and spores are dispersed in high quantities in the air, carried by air currents, before falling onto the ground in a thin coating called pollen rain.

In some areas, the high volume of pollen and dispersed spores can cause exposed land and water surfaces to turn yellow due to the pollen rain. Though it may not be a high-level measurement of the vegetation in the area, pollen rain can be used as a snapshot of the vegetation of a certain region. It can become a ‘pollen print’ to identify the region.⁴

Additionally, because pollen and spores are microscopic and invisible to the naked eye, they can easily become trapped on nearly any surface. This characteristic makes them valuable in criminal investigations, as they can be used to link a suspect or piece of evidence to a specific region or crime scene.⁴

Analyzing Pollen Evidence

Forensic palynologists typically undertake two specific types of investigations.⁴

The first type involves specific situations with victims, suspects, crime scenes, and objects suspected to be evidence associated with one of these situations. This investigation requires the palynologist to visit the crime scene, collect comparison samples and then examine other kinds of evidence that may be related to the crime scene.

The palynologist must have knowledge of plant ecology and communities around the crime scene, as well as other factors that may impact it, such as soil and climatic features, including vegetational changes.⁴

The second type of investigation involves establishing a geolocation for samples of an unknown origin. This would require the forensic palynologist to remove vacuumed samples of clothing from suspects or take samples from contents of items seized as evidence, such as packages, laptops, suitcases, abandoned vehicles and more. These samples may reveal pollen and spore clues that may lead to the origin or location of where the objects were made or used.⁴

Forensic palynologists may use several different types of analytical methods for investigating pollen and spores collected from crime scenes and suspects, including microscopy, spectroscopy, and molecular methods for pollen analysis.⁴

DNA barcoding may also be used to identify the species, which targets specific parts of the plant genome unique to a particular species.⁵

As pollen analysis is a destructive process, further forensic testing and analytical sequence have to be considered to reduce the risk of contamination, as the evidence may have to be analyzed again.⁵

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Solving Crimes with Pollen: Case Studies

An Austrian murder mystery in the 1950s consisted of a man that disappeared whilst traveling. The investigation led to a suspect, who was found to have mud on his boots contaminated with fossilized pollen grains that were 20 million years old.

These pollen grains could be tracked to being from only one small area on the Danube River. After confronting the suspect with this evidence, he confessed and led the police to the body, to the exact location the pollen suggested.⁶

Applications of Forensic Palynology

Forensic palynology can also be used for other applications, including investigating historical events or items, such as the Shroud of Turin, a cloth that some believe was used to cover Jesus’ body before burial. This was one of the highest-profile examples of pollen being used as a critical piece of evidence to verify the origin of an object.⁶

Another high-profile case authenticated the Gondar Hanging, which was gifted to the Royal Ontario Museum in Toronto, Canada. This item was reported to have been produced in Ethiopia in the 17^th or early 18^th century, and the museum curators wanted to confirm its authenticity through the pollen trapped in the fabric.⁶

Other applications also include identifying the season of the crime or helping to reconstruct the environment in which a crime occurred.^4,5

Challenges and Considerations

While forensic palynology has its advantages for many applications, this discipline also faces some challenges.⁵

Like most forensic evidence, a key challenge for palynologists includes timing. Forensic palynologists need to be called early on when investigating a crime to ensure the better value of the samples collected and reduce contamination.⁵

Pollen and spores are light, small, and easily recycled, and this means a crime scene can be easily contaminated with shoes or search teams that cut or remove foliage while looking for evidence.⁵

Additionally, pollen retrieved from a suspect matching evidence from a crime scene does not necessarily mean they have committed a crime, and it could just suggest the person visited the area recently.⁶

It could also have been transferred and not have been due to visiting the area themselves.⁴

Another challenge includes accurate interpretation of evidence, as there may not be a large population of people that are trained to analyze palynological samples, and due to the extent of knowledge that is required to be a forensic palynologist, it may be difficult to come to an agreement depending on the level of understanding of various factors such as soil and climate.^4,6

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The Future of Forensic Palynology

With the rapid evolution of technology and advancements in many scientific industries, the future of forensic palynology may grow exponentially to aid in effective crime scene investigation.⁶

Advanced technologies within laboratories have also shown that DNA can be recovered from a single pollen grain, and DNA barcoding can be used to identify multiple taxonomy groups and parts of an organism that do not show in the morphology.

DNA barcoding is the fastest way to differentiate between pollens, and this can be used to propel evidence used in crime cases.⁶

Additionally, high-throughput DNA sequencing, which has led to spore DNA barcoding, can enable researchers to sequence many samples of DNA simultaneously without separating them first.⁶

Using these scientific methods and others demonstrates the potential of forensic palynology, with significant implications for more sophisticated crime-solving applications.⁶

References

1. What is forensic science? BBC Science Focus Magazine. Accessed June 11, 2024. https://www.sciencefocus.com/the-human-body/what-is-forensic-science.
2. Trace evidence: The role in forensic science " forensic science " college of pharmacy " University of Florida. UF monogram. Accessed June 11, 2024. https://forensicscience.ufl.edu/2022/10/14/trace-evidence-the-role-in-forensic-science/.
3. Carloss T. A piece of evidence the size of a quarter helped Akron Police solve a 2000 murder. News 5 Cleveland WEWS. March 5, 2018. Accessed June 11, 2024. https://www.news5cleveland.com/news/local-news/oh-summit/this-piece-of-evidence-the-size-of-a-quarter-helped-akron-police-solve-a-2000-murder.
4. Bryant VM. Pollen and spore evidence in forensics. Wiley Encyclopedia of Forensic Science. Published online March 14, 2014:1-16. doi:10.1002/9780470061589.fsa085.pub2
5. Ezegbogu MO. Identifying the scene of a crime through pollen analysis. Science & Justice. 2021;61(3):205-213. doi:10.1016/j.scijus.2020.12.002
6. Alotaibi SS, Sayed SM, Alosaimi M, et al. Pollen Molecular Biology: Applications in the forensic palynology and future prospects: A Review. Saudi Journal of Biological Sciences. 2020;27(5):1185-1190. doi:10.1016/j.sjbs.2020.02.019

Further Reading

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• Collecting Evidence at a Crime Scene
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• Forensic Investigations of Natural Disasters
• Forensic Identification in Mass Disasters