Palynology is the science that studies contemporary and fossil palynomorphs, including pollen, spores, orbicules, dinoflagellate cysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter (POM) and kerogen found in sedimentary rocks and sediments.
Forensic Hall of FAME:
Pollen can tell a lot about where a person or object has been, because regions of the world, or even more particular locations such a certain set of bushes, will have a distinctive collection of pollen species.
There are four major characteristics of pollen that make it a useful scientific tool:
- (1) Microscopic size – most pollen grains are 10-70 um in diameter (there are 1,000 um in a mm).
- (2) Abundance - pollen is everywhere.
- (3) Resistance to degradation - they can be preserved in rocks for millions of years.
- (4) Complexity – most plant species produce pollen or spores that are different from pollen of other plant species.
Pollen evidence is as good as any other form of evidence, but it takes carefully implemented precautionary measures to ensure this evidence remains viable in court proceedings. Pollen samples must be very closely monitored and safeguarded against contamination to maintain their integrity.
Palynology can also be used to fight terrorism by determining the origin of manufacture of such biological weapons.
CASE STUDIES
CASE STUDY1:
>>Pollen helps war crime forensics
Researchers have revealed how a team of forensic experts used pollen to help them to convict Bosnian war criminals.
Professor Tony Brown of the University of Exeter used the method to link mass graves in Bosnia, which supported the case for genocide by the prosecution.
He says pollen and unchanging soil characteristics can “provide strong circumstantial evidence placing a vehicle or person at a crime scene”.
The research was presented at the BA’s annual Festival of Science in Exeter.
“Forensic pollen analysis has made a significant contribution to the investigation of war crimes in Bosnia,” Professor Brown explained.
Bosnian war criminals tried disguising their acts of genocide by exhuming mass graves and reburying bodies in smaller graves, claiming they were the result of minor battles.
Laborious search
The prosecution at the UN war crimes tribunal needed to show that the many “secondary” burial sites could be linked to a few “primary” ones, to prove that mass graves had initially existed.
Professor Brown was part of the North East Bosnian Mortuary Team which conducted forensic examinations of mass graves. The team, which worked under constant UN guard, examined 20 sites over a four-year period from 1997.
Soil samples were taken from skeletal cavities, inside the graves, and from around the suspected primary and secondary burial sites.
Pollen from the soil samples was cleaned with powerful chemicals before being analysed, and the mineralogy of the soil itself was examined.Once complete, matches could be made between different samples – ultimately leading to links between primary and secondary burial sites.Professor Brown said: “For example, one primary execution and burial site was in a field of wheat. When bodies were found in secondary burial sites they were linked to the primary location through the presence of distinctive wheat pollen in soil recovered from the victims.”
Independent ballistics work was in 100% agreement with the conclusions of the pollen and soil analysis, he added.
Overall, the work formed a significant component of the generic body of evidence used against those involved in the Srebrenica atrocities.
Professor Brown said a case in point was the conviction of Radislav Krstic, commander of a military unit which participated in the massacres in and around Srebrenica in the summer of 1995.
CASE STUDY 2:
Two male intruders entered a house in which the sole female occupant slept having left the back door unlocked for the return of her live-in boyfriend. She awoke and saw strangers in her bedroom. The intruders ran off, one leaving a jacket behind on the kitchen floor. One of the intruders subsequently returned to recover his jacket, but in his rush to leave the house he brushed against a flowering Hypericum bush growing just outside the back door. A suspect was arrested later that day and charged with indecent assault on a female and burglary, but denied any involvement and refused to name any associate.
A day following the offence the suspect’s clothes were taken for forensic examination. Pollen analysis of selected parts of his clothing showed that his track pants contained 14% Hypericum pollen, denim jacket 24%, and polo shirt 27.5%. Traces of Hypericum pollen occurred on other items. Most of these pollen grains still had their cell contents preserved and were on the clothing in clumps consistent with having recently been collected by the clothing and not having been aerially dispersed. The pollen from the Hypericum bush was identical in colour, shape, development, and size range to the pollen from the clothing. The clothes had so much Hypericum pollen on them that they had to have been in direct and intimate contact with a flowering bush.
Pollen evidence is by its nature circumstantial and often cannot be used on its own to convict, or more strictly to determine the truth. The suspect may have been in contact with Hypericum elsewhere, but detailed investigations indicated that this was unlikely. In 30 years of New Zealand forensic work Hypericum had only ever been found on clothing in trace amounts. This is but one way in which forensic palynology can assist law enforcement agencies to determine the history behind a criminal action, and demonstrates that forensic palynology should be considered as an integral part of any criminal investigation.
Summary:
Forensic palynology is in its infancy. It is seldom used in other regions, and is not yet accepted or recognized as being valuable evidence in most court systems. There are also still misconceptions about what types of information forensic pollen samples can provide. Often police and other investigators regard forensic samples, and the testing results, only as tools that can be used to “convict” a suspect.
Often, many types of forensic data, such as pollen results, do not actually “convict” a suspect. Instead, the samples are useful tools that can point investigators in the “right” direction, or narrow the number of suspects, or perhaps even eliminate a person as a prime suspect. Nevertheless, even in this type of supporting role, forensic palynology can become a powerful tool of the forensic scientist
Reference links:
http://news.bbc.co.uk/2/hi/science/nature/3640788.stm
http://www.thebatt.com/2.8526/forensics-studies-look-to-pollen-1.1224833
http://www.fsijournal.org/article/S0379-0738%2805%2900621-3/abstract
http://www.crimeandclues.com/index.php/physical-evidence/trace-evidence/67-forensic-palynology-a-new-way-to-catch-crooks
