thumb|1871 plate of magnified pollen grains
Forensic palynology is a subdiscipline of palynology (the study of pollen grains, spores, and other palynomorphs), that aims to prove or disprove a relationship among objects, people, and places that may pertain to both criminal and civil cases. Pollen evidence can also reveal the season in which a particular object picked up the pollen. Recent research into forensic palynology has seen advancements in DNA barcoding from pollen, to the level of singular pollen molecules, allowing DNA profiles to be created from singular palynomorphs, streamlining the efficiency and accuracy of taxonomic identification.
Palynology is the study of palynomorphs – microscopic structures of both animal and plant origin that are resistant to decay. This includes spermatophyte pollen, as well as spores (fungi, bryophytes, and ferns), dinoflagellates, and various other organic microorganisms – both living and fossilized. There are a variety of ways in which the study of these microscopic, walled particles can be applied to criminal forensics.
In areas such as New Zealand, where the demand for this field is high, forensic palynology has been used as evidence in many different case types that range anywhere from non-violent to extremely violent crimes. pinpoint the scene of a crime, and catch a burglar who brushed against a Hypericum bush during a crime. Because pollen has distinct morphology and is relatively indestructible, it is likely to adhere to a variety of surfaces often without notice and has even become a part of ongoing research into forensic bullet coatings.
Present status
Forensic palynology is an evolving forensic science application mostly utilized in countries such as New Zealand, Australia, and the United Kingdom. Moreover, there is a limit in forensic palynologists as most skilled palynologists do not enter the forensic palynology field. As becoming a Forensic Palynologist requires rigorous training and education, one must attain a PhD with sufficient background in studies such as forensic science, botany, ecology, geography, and climatology. Recently however, there has been expansive research into areas that have yet to well documented, such as the study that did research on the effects that an arid climate had on pollen analytics that took place in southeast Spain. This study not only expanded the use of forensic palynology into new parts of the world that have not yet been introduced to this science, but also collected results that outline a proper method for pollen spectra collecting that is effective in arid conditions. This database creation is allowing forensic palynology to be used in a more broad area now, as data for both high altitude pollen assemblage and non-seasonal soil data has been collected.
Duties
In terms of criminal investigation, forensic palynologist services are requested from cases such as forgery, rape, homicide, genocide, terrorism, drug dealing, assault, and robbery. Scrubbing, scraping, washing is essential for retrieval of palynomorphs from various materials. And utilize other methods like police photographers, cartographers, and botanists. It is vital for the Forensic Palynologist to visit the crime scene before the Crime Science Investigators (CSI) or Scenes of crime Officers (SOCOs) to avoid disturbance of environmental evidence and contamination.
Disadvantages
One of the main disadvantages in this field is the lack of trained specialists. Many things could go wrong and invalidate any samples collected, especially if the personnel handling them is not experienced. On the subject of experience, contamination is another major problem that can invalidate the use of a sample as evidence; therefore, it is important that samples are collected early on with collection sites identified depending on the case.
Limited access to international databases can also prove to be an issue when it comes time for the analyst to identify pollen evidence to a specific family or genus of plants. Currently, a database from Austria called PalDat exists but there are no known databases to exist in North America. This means that forensic palynology evidence is rarely submitted due to lack of history in the courts, and lack of application in most countries.
Methods
Sample collection
Because pollen can be easily picked up by anyone, it is important that pollen samples are collected as soon as possible to prevent contamination from outside sources. Samples then need to be prepared and placed on slides in order to fully be safe from contamination. For example, if the pollen evidence is used in court, then the additional context would be useful.
Sample collection methods will vary depending on the case investigation and on the collector. They are then neutralized, and the extracts are stained and mounted onto slides for microscopic examination.
United States, 1970
The first cases that involved forensic palynology in the United States was in 1970, where Honeybee pollination studies were issued. During this time honey pollen analysis began growing as the United States Department of Agriculture (USDA) ensured beekeepers a higher world market price for their honey, subject to the condition that the honey was produced on USA soil. Thus, honey samples were sent for pollen analysis to confirm whether the honey was produced in the USA. Generally, most of the cases during this time involved lawsuits concerning beekeepers. For example, a Michigan beekeeper was suspected of importing beehives from the southeastern USA that weren't inspected for mites. This led to the USDA inspecting honey samples where it was concluded that they were imported from the Southeastern region of USA. Due to that the honey contained floral types common to the Southeastern region and not found in Michigan.
United Kingdom, 1993
An example concerning Forensic Palynology in the United Kingdom, which took place during 1993, handled by Patricia Wiltshire. It involved a murder case in which the body was laid on soil that preserved pollen. Wiltshire then found traces of walnut pollen in the soil and suspect's shoes, however, the walnut pollen found was unusual as there was no walnut site nearby. However, It was later discovered that a walnut tree was cut down thirty years before and the walnut pollen remained. the pollen was then analyzed and linked to the suspect in the crime scene. Thus, the walnut pollen provided a significant role solving the case.
New Zealand, 2005
After a home invasion, two burglars brushed past a Hypericum bush outside of the house. One of the burglars was brought in as a suspect, but all evidence was circumstantial, and the man did not confess. Analysis of his clothes revealed the Hypericum pollen. The presence of pollen is ubiquitous, but in this case, the pollen was clumped onto the clothing (rather than dusted) and did not seem to be simply the result of air dispersal. It was ultimately concluded that "the clothes had so much Hypericum pollen on them that they had to have been in direct and intimate contact with a flowering bush."
The pollen assemblage created from the submitted samples indicated the victim was in the north-eastern United States before her death. The individual taxa of plant species observed in the assemblage also indicated that the victim lived in, or spent much of her time in, a developed, urban environment. The assemblage also captured pollen of the Lebanese cedar tree (Cedrus libani), native to the Eastern Mediterranean region of Europe. The species of cedar observed in the assemblage was thought by investigators to most likely be from an ornamental piece in a park or other conservation area. This is when the investigators discovered individuals of the Lebanese cedar tree in the Arnold Arboretum, a public park that is a part of Harvard University.