- Education and Science
The Use of Pollen in Forensic Science
Pollen as evidence
Suspended in mid air, in your car seat, inside ancient rocks, in your pants pockets, in your hair and in your home- pollen is everywhere!
Although produced in huge quantities, pollen is extremely microscopic in size and hence invisible to the naked eye. Approximately 240,000 species of flowering and coniferous plants produce the fine dust in a range of diverse shapes, colors and sizes.The pollen grains of a particular species even differ from that of its closest relatives, and hence leave a different “fingerprint” for every plant in the world.
Since the last few decades, fingerprints from pollen have become the dominion of many forensic scientists throughout the world, and have proven to be the main ingredient of one of the most powerful techniques in trace and contact evidence- forensic palynology.
Pollen can help destroy or prove alibis, link a suspect to the scene of a crime, or link something left at the crime scene to a suspect. It can also help to determine what country or state drugs, food, merchandise, and antiques among other things, have come from.
Forensic palynology in a 60's case
What is forensic science?
The word forensic comes from the Latin adjective forensis, which means “before the forum or public”, and which refers to something “pertaining to or used in a court of law”
Forensic science is science that is used to answer questions of interest in a court, or in the justice system. In other words, any science used for the purposes of the law is a forensic science. This may be in relation to a crime or a civil action.
It was stated by French forensics pioneer Edmond Locard, that “every contact leaves a trace”. This is the defining principle for forensics. Trace evidence may be clothing fibers, a fingerprint, or DNA from blood or hair; and today, forensic scientists enjoy a beautiful addition to the list of forensic tools- pollen.
The facts developed by forensic scientists are based on scientific investigation, not circumstantial evidence or the sometimes unreliable testimony of witnesses. Forensic scientists at times, prove the existence of a crime or make connections to a crime. They provide information and expert opinion to investigators, attorneys, judges, and juries which can be extremely helpful in determining the innocence or guilt of the accused.
Forensic scientists are entirely responsible for the work they perform; no one else can write their reports nor testify to their opinions. However, it takes teamwork to solve a crime. Forensic scientists work closely with police officers, sheriff's deputies, prosecuting and defense attorneys, DEA, CIA, and FBI agents, immigration workers, and crime scene investigators, to name a few.
The rule of law is based on the belief that the legal process results in justice; and forensic scientists play a critical role in the path to justice by using science and technology in the search in civil, criminal and regulatory matters.
Among the world’s forensic scientists is a small group of experts who use pollen and spores to link objects and people to crime scenes- these experts are called forensic palynologists.
Upon the identification of pollen, spores or other microscopic plant bodies, and the determination of where and when they originated, forensic palynologists are able to ascertain that a body or other object was in a certain place at a certain time.
The use of pollen in forensic science
As known by most, DNA is the current darling of forensic science. It is faster to process than a pollen assemblage, which must go through a painstaking chemical treatment to remove the material surrounding it and the cytoplasm and sex cells inside it; and then be carefully analyzed through a microscope to identify each individual species.
Palynologists can determine a plant group using a standard light microscope at up to 1,500 times magnification. However, the higher the resolution of the scanning microscope required to get the job done, the more expensive and time consuming the identification process will be.
So why even bother with pollen as a forensic tool? There are many answers to this question:
The size of pollen grains
Pollen is very microscopic in size, and hence criminals do not realize that they have taken it with them, or have left it behind.
The durability of pollen grains
Pollen’s cell walls are very durable, and hence the grains can survive for millions of years. In one case in Wales, pollen from a walnut tree that had been cut down 80 years prior to the case, linked suspects to the scene of a crime where the tree had once stood.
The diversity of pollen
Because there are hundreds of thousands of flowering and coniferous plants that produce pollen, there is a lot of diversity among the “fingerprints” left by pollen. This diversity lends to greater specificity when palynologists attempt to link pollen to particular plants and places.
Pollen offers a new type of evidence
There was a time when the absence of DNA meant that no evidence was present- DNA was considered the God of evidence. However throughout the world, people are now looking at things differently. Pollen has now become a good telltale sign for where things are coming from.
The global use of pollen in forensic palynology
On a global scale, it is difficult to establish precisely when the field of forensic palynology began. Attempts made prior to the 1950’s whether successful or not, probably did not gain much public attention and therefore were not reported. The possibility also exists that results made by employing palynological techniques may have been purposely hidden from the media in order not to alert criminals about its use.
In the United States the field is reported as having debuted in the mid- 1970’s, when the Department of Agriculture first used pollen to ensure that bee- keepers receiving domestic subsidies were actually making their honey in the U.S. Since then, there has only been a handful of criminal cases that have employed palynology techniques.
Interest has grown at the federal level since 2001, when the U.S. government was eager to do anything to find out who had committed the September 11th attacks and to prevent it from happening again. Pollen has since been used in several terrorism investigations. The burned clothing of suicide bombers, for example, may retain pollen that could hold clues to their origin.
In the late 1990’s pollen was used to investigate war crimes. Forensics experts working with the United Nations in Bosnia found pollen evidence indicating that more than 2000 Bosnian Muslim men and boys executed over five days in 1995 during the Bosnian war had later been moved from five large mass graves to several smaller ones scattered across the countryside to cover up the massacre.
Around the world, palynological techniques have been used to break up cocaine rings, authenticate antiques, find counterfeit Viagra and antimalarial drugs, and even track down stolen sheep and a lawn mower.
Today, the country of New Zealand leads the world in the use of forensic palynology, and the acceptance of this type of evidence in courts of law. There is the hope that this crucial addition to forensic science will continue to gain popularity, and that its important and diverse techniques will become accepted in most countries throughout the world.