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Forensic Palynology

Forensic Palynology. Jaclyn Seelagy Department of Forensic Science at George Washington University. What is Forensic Palynology ?. Use of pollen and spores in criminal investigation. Used often in New Zealand, Australia, UK. WHAT IS FORENSIC PALYNOLOGY? .

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Forensic Palynology

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  1. Forensic Palynology Jaclyn Seelagy Department of Forensic Science at George Washington University

  2. What is Forensic Palynology? • Use of pollen and spores in criminal investigation. • Used often in New Zealand, Australia, UK.

  3. WHAT IS FORENSIC PALYNOLOGY? A type of associative evidence. Used to make associations between people, between a suspect and a crime scene, any type of evidence and a particular location Ex: The transportation history of drugs. Can also help determine when/where a body was dumped.

  4. A Few Definitions • Pollen: grains produced by flowering or cone-bearing plants to carry male sex cells to other plants. • Spores: small reproductive bodies of plants and other organisms that don’t produce pollen: ferns, mosses, algae, fungi, etc. • Locard’s Exchange Principle: Whenever two objects come together, there is an exchange of material (the principle behind trace/associative evidence).

  5. What makes Pollen so useful? • Size • Microscopic. • Generally goes unnoticed. • Suspect picks up evidence of his/her presence at a crime scene without realizing it, therefore without taking precautions. • Variable morphology • Durability • Limited dispersal.

  6. Variations in Morphology • Different types of pollen look different under a microscope. • Shape (sphere, oval, triangle, etc). • Sculpture patterns on surface (spines, granules, pores). • Wall structure/thickness. Bruce and Dettmann, p. 91

  7. Durability • Wall of a pollen grain contains sporopollenin. • Survives almost anything including bleach. • Can recognize a pollen grain’s distinctive shape even after it has been on a body or a suspect’s clothes for a long time. • Traces of pollen can remain on clothing for days if the clothing isn’t washed.

  8. Dispersal • Wind-dispersed pollen • Plant produces a lot of it. • Pollen can go fairly far from the plant. • Only gives a general idea of location. • Animal-dispersed pollen • Includes insects, bats, birds, etc. • Tends not to go far from the plant. • Can associate a suspect or object with a narrow scene. • Direct contact (brushing against a plant). • leaves larger amounts of pollen. • pinpoints a subject’s proximity even more exactly.

  9. METHODS

  10. Methods • Samples analyzed microscopically. • Samples taken from an item (suspect’s clothing, corpse, wheel wells of a car, etc.) • Individual grains compared to reference samples for identification. • Examiner counts each type of pollen, calculates percentages. • Compares these percentages to the pollen content of regional control samples to see if they resemble the pollen of a scene.

  11. Methods (cont’d) • Can also use DNA to determine plant species from pollen (more time consuming, expensive) • Certain seasonal pollen grains can help determine season of death: • While pollen on the ground or clothing accumulates over time, pollen only remains in the air temporarily. • A person inhales pollen, trapping it in his/her nose, or traps it in hair or eyebrows. • Pollen found in hair or nose samples from a body was likely trapped there in the few days before death.

  12. QUESTIONS?

  13. References • Horrocks M, Walsh KAJ. Fine resolution of pollen patterns in limited space: differentiating a crime scene and alibi scene seven meters apart. J Forensic Sci 1999;44(2):417-420. • Mildenhall DC. Hypericum pollen determines the presence of burglars at the scene of a crime: an example of forensic palynology. Forensic Sci Int’l 2006;163:231-235. • Horrocks M, Walsh KAJ. Pollen on grass clippings: putting the suspect at the scene of the crime. J Forensic Sci 2001;46(4):947-949. • Brown AG, Smith A, Elmhurst O. The combined use of pollen and soil analyses in a search and subsequent murder investigation. J Forensic Sci 2002;47(3):614-618. • Bruce RG, Dettmann ME. Palynological analyses of Australian surface soils and their potential in forensic science. Forensic Sci Int’l 1996;81:77-94.

  14. References (cont’d) • Editorial: Mildenhall DC, Wiltshire PEJ, Bryant VM. Forensic palynology: why do it and how it works. Forensic Sci Int’l 2006;163:163-172. • Mildenhall DC. An unusual appearance of a common pollen type indicates the scene of the crime. Forensic Sci Int’l 2006;163:236-240. • Bull PA, Morgan RM, Segovsky A, Hughes GJA. The transfer and persistence of trace particulates: experimental studies using clothing fabrics. Sciene& Justice 2006;46(3):185-195. • Montali E, Mercuri AM, Grandi GT, Accorsi CA. Towards a “crime pollen calendar”—pollen analysis on corpses throughout one year. Forensic Sci Int’l 2006;163:211-223. • Eliet JR, Harbison SA. The development of a DNA analysis system for pollen. Int’l Congress Series 2006;1288:825-827.

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