Forensic PalynologyPresentation by Francesca Beer
“( r ) Pollen – The wind likewise transports pollen dust, whose constant presence is noted on garments and on the body during the summer season. It is found in the ears as well as in the nostrils where the pollen produces the inflammation called hay fever.” “( u ) Mushroom Spores – …On the other hand, spores collected in dust are often quite characteristic and permit us up to a certain degree to determine what the bearer has been recently doing, such as walking in a wood, collecting mushrooms, etc.” ~Edmond Locard, 1930 “The Analysis of Dust Traces, Part II” The American Journal of Police Science Volume 1, Issue 4
What is Forensic Palynology?• Palynology is the study of fossil and modern ‘palynomorphs’• A palynomorph is defined as a particle made of organic material that measures between 5 and 500 micrometers and is found in sedimentary deposits• The most commonly studied palynomorphs are pollen and spores, leading many to falsely believe that palynology is in fact the study of pollen and spores.
What is Forensic Palynology?• Forensic Palynology is the application of palynology to legal issues and the law.• Forensic palynology primarily analyzes spores and pollen as a form of trace evidence.• Although things like fossilized organic structures, arthropod organs, and certain worms and protists are considered palynomorphs, Forensic Palynology is more concerned with spores, pollen, and other powered minerals and how they can be used in a legal context.
What can Forensic Palynology do?• Forensic Palynology can: – “Relate a suspect to a crime or discovery scene – Relate an item left at a crime or discovery scene to a suspect or victim – Relate an item found on the suspect or victim to a crime or discovery scene – Relate an item at the discovery scene to the crime scene – Prove or disprove an alibis
What can Forensic Palynology do? – Determine the travel history of items – Provide information of the environment an item has come from or was in – Aid police in investigation – Determine if a body was moved, pre, post, or peri mortem – Determine approximately how old human remains are” – …and much more – Mildenhall, D., P. Wiltshire, and V. Bryant. "Forensic Palynology: Why Do It and How It Works." Forensic Science International 163.3 (2006): 163-72. Print.
How does Forensic Palynology Work?• Forensic Palynology is based upon the Locard’s Exchange Principle, that is, that “every contact leaves a trace.”• It uses the pollen and spores of native plants of certain geographical locations to place someone or something somewhere – Examples are: placing a suspect at a crime scene, supporting or disproving an alibis, placing an item at a crime scene, and much more.
How does Forensic Palynology Work?• Forensic palynology primarily uses microscopy to compare, identify, and analyze samples of pollen and spores.• The morphology of pollen and spores is incredibly diverse, allowing identification to a specific taxon, normally accurate to genus or even species, by visual comparison.• A pollen assemblage is the number of identified pollen and spores found in a sample.
How does Forensic Palynology Work? Morphology of Pollen and Spores• The diversity of morphology of the pollen and spores is manifested in their cell wall structures. Characteristics include: – Size – Shape – Wall Pattern – Wall Thickness – Apertures• The diversity in these characteristics allows relatively precise identification.
Scanning Electron Microscope (SEM) image of miscellaneous pollen particleshttp://upload.wikimedia.org/wikipedia/commons/a/a4/Misc_pollen.jpg
How does Forensic Palynology Work?• While Scanning Electron Microscopes are preferred for their accuracy and clarity at such small scales, most palynologists can only use light microscopes for identification due to lack of funding or access to an SEM.• When identifying a pollen grain or spore, a photograph or known sample is required.• There are various databases of pollen grains and spores, such as the Global Pollen Database, the European Pollen Database, etc.• Occasionally, palynologists will request samples of similar morphology from herbaria or fungaria for comparison.
Daisy Pollen under Light Microscope and SEM Light Microscope Scanning Electron Microscope Light: http://www.abc.net.au/reslib/201110/r841964_7864873.jpg SEM: http://www.abc.net.au/reslib/201110/r842009_7866030.JPG
How does Forensic Palynology Work?• Palynologists can compare two soil samples and, depending on the percent composition of the identified spores and pollen in the soil, can determine if the samples originated from the same location.• Palynologists will never find two identical samples, however, using the similarity of the percent composition of the pollen and spores in the soil, they will be able to identify which samples are significantly similar or significantly different, that is, if they came from the same location or not.
Why use Forensic Palynology?• Pollen and spores are very durable – able to last millions of years in the correct environment and are resistant to chemical and mechanical damage.• They are small and are easily trapped in clothes and fibers, as well as soil, skin, and other mucous membranes.• They are abundant in almost all environments.• They are also rather easily transferable between places, people, things, etc.• Because of this, they are a reliable form of trace evidence.
Why use Forensic Palynology?• Since pollen and spores are so durable, they can leave a vegetative history in the soil. This vegetative history is unique to the area, which is why soil samples are able to be used to identify locations• Similarly, their endurance allows them to stick to clothes, skin, etc, for quite a long time without being degraded or destroyed, allowing them to be used as evidence even years after a crime.
Palynology as a Forensic Discipline• Forensic Palynology is not practiced often in the United States, but is widely accepted and used in New Zealand, Australia, and the United Kingdom.• As a tool of forensic science, palynology is quite labor intensive, expensive, and requires a certain, rare level of expertise.• Because of this, as well as the ignorance of palynology’s potential as a forensic discipline, many other countries, especially the United States, have not invested much in it.
Forensic Palynology Cases• Two males entered the house of a woman and her live-in boyfriend through the back door. The woman was home alone, asleep, with the back door unlocked for her boyfriend to get in the house when he returned. The woman awoke to sounds in the house and discovered the intruders, who quickly fled. One of the intruders left his jacket at the house, and later returned to retrieve the jacket. In a rush, he carelessly brushed against a ‘Hypericum’ plant that was blooming by the back door.
Forensic Palynology Cases• A suspect was arrested and, after analysis of his clothes, the palynologists found that the concentration of Hypericum pollen was unable to have been swept onto the clothing by wind dispersal and they had to have been in direct contact with the bush. They also found the pollen from the bush to be identical to the pollen sampled from the Hypericum bush in question.• The palynological evidence alone did not convict the suspect, but along with other evidence obtained, as well as positive identification of the suspect by the victim, the suspect was charged with burglary.• Mildenhall, D. "Hypericum Pollen Determines the Presence of Burglars at the Scene of a Crime: An Example of Forensic Palynology." Forensic Science International 163.3 (2006): 231-35. Print.
Forensic Palynology Cases• A girl was walking the streets of New Zealand when she was grabbed, threatened, and raped. The victim identified a scene, but there were questions as to its reliability. During the investigation of the area, they found, in great number, ‘Coprosma’ shrubs, a relatively common shrub found in the area. They sampled pollen from the shrubs and found a very unique characteristic: The pollen sampled from the scene had fungus growing on it, small branches of the fungus even growing into the pores of the grains.
Forensic Palynology Cases• They examined the victim’s clothes and found Coprosma pollen, and upon further examination they found that the pollen of her clothes matched morphologically and had the same fungus growing on the grains, similarly the branches of the fungus growing into the pores.• It was concluded that the scene must have been the scene of the crime due to this.• Mildenhall, D. "An Unusual Appearance of a Common Pollen Type Indicates the Scene of the Crime." Forensic Science International 163.3 (2006): 236-40. Print.
References• Locard, Edmond, and D. J. Larson. "The Analysis of Dust Traces. Part II." The American Journal of Police Science 1.4 (1930): 401-18. Print.• Mildenhall, D. "An Unusual Appearance of a Common Pollen Type Indicates the Scene of the Crime." Forensic Science International 163.3 (2006): 236-40. Print.• Mildenhall, D. "Hypericum Pollen Determines the Presence of Burglars at the Scene of a Crime: An Example of Forensic Palynology." Forensic Science International 163.3 (2006): 231- 35. Print.• Mildenhall, D., P. Wiltshire, and V. Bryant. "Forensic Palynology: Why Do It and How It Works." Forensic Science International 163.3 (2006): 163-72. Print.• Walsh, Kevan A.J., and Mark Horrocks. "Palynology: Its Position in the Field of Forensic Science." Journal of Forensic Sciences 53.5 (2008): 1053-060. Print.