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Medico-Legal Update

Significance of Palynology in Forensic Problems

Author(s): Dr. Kapil Dev

Vol. 5, No. 1 (2005-01 - 2005-03)

Abstract

Palynology, the study of pollens, though used in several cases of forensic significance has not made much headway in India. It is in this backdrop some important cases where the pollen played a vital role are discussed.

Keywords: Pollen Analysis; Forensic science.

INTRODUCTION

Study of the pollens, Palynology, is now gaining importance in forensic casework analysis. They not only help to link the particular type of flowers found at a crime scene but also to the time (season), when they are in bloom. Forensic palynology refers to the use of pollen and spore evidence in legal cases (Mildenhall,1982). It also includes legal information derived from the analysis of a broad range of microscopic organisms e.g. Dianoflagellates, Acritarchs and Chitozoans that can be found in both fresh and marine environments (Faegri et.al., 1989).

Because of their microscopic entity, pollens are different type of trace evidence found at the scene of crime. In almost every case pollens are expected to be present, be it in wearing apparels, body parts especially in hairs, shoes, etc. However, forensic palynology has not made much headway in India because of the difficulties and problems that are encountered in their isolation and identification work.

Pollen grains can be differentiated by their external morphology, which may be circular, ovate, bean-shaped, spinecular, etc. Their variable shape, size, aperture, and wall characteristics are very helpful in their identification. The exine (outer layer) of the pollen is resistant to acetolysis, physical and biological degradation. Because of this property of exine, pollen grains can be found well preserved at a crime scene for a long period. They are carried by different media such as air, animals including man, insects such as bees, butterfly etc.

One of the earliest reported cases using palynology occurred in Sweden in 1959. A woman was killed in May during a trip in central Sweden. Palynological examination was done to determine whether or not the women was killed where she was found or the murder took place elsewhere and then the body dumped at the site of the alleged crime scene. The examination suggested that the murder took place elsewhere because the dirt lacked pollen from plants common in the area where the body was found (i.e. Plantago, Rumex,and Grasses).However the later interpretation was that murder took place in May because the Pollination during that time was over (Erdtman, 1969). Mildenhall(1988) suggested that pollens may be present in the dirt collected from the clothing’s, skin, hair, shoes, or car of a victim and might prove useful links between the victim and scene of crime.

A stolen vehicle can be linked with crime after comparing the mud found on that vehicle. The pollen evidence may be useful in linking with a specific crime or a specific geographical area (Brown and Llewellyn, 1991). Mildenhall (1992) reported a case of murder after kidnapping and sexual assault. In this case, pollen fingerprint from the woman’s short was found identical to the pollen fingerprint extracted from the suspect’s sweater and from his soiled pants. Pollens of Salicornia species (Family Chenopodiaeace) in northwest Canada and Alaska were studied. The pollen grains from bodies of ancient people were examined which provided clues to their diet and domicile.

Pain (1993) referred that pollen and spores are abundant in the soil, dirt and dust samples.

Horrocks et. al. (1998a) showed the significance of pollen evidence to assist the court. He presented the assessment of palynology using the likelihood ratio in forensic court trials. To assist his findings, he presented three cases of alleged rape and establishing time of death.

Horrocks et. al. (1998b) stated that the soil samples for palynological analysis are very useful in forensics. He stated that the pollen samples within a localized area are similar and show the difference from distant localized areas. Chenopodiaceae pollen found in the stomach of Kwday Dan Ts‘inchi (A person found dead long ago in a glacier in Britain) were studied and these were used to distinguish pollens of the native Chenopod genera such as Atriplex, Chenopodium, Eurotia, Suaeda, and Salicornia. (Petra et.al.2005)

In a recent case the Central Texas Authorities seized a supply of marijuana and wanted to know if it had been grown locally or was imported. Pollen studies indicated that the pot could have been grown in a region extending westward from Central Texas to Phoenix, Arizona and therefore confirmed that the seized drugs were not shipped from a foreign country.

In a related example, the process of turning Cocoa leaves into Cocaine begins when the leaves are picked, dried in the open, processed in outdoor areas, and then refined into Cocaine (Weatherford, 1987).

Pollen fingerprints can be very useful in determining the source of origin of the cocaine samples. Pollen samples from the stomach contents or excrements have provided a clue to several deaths in Brazil. The pollens of a plant, Serjania lethalis (Sapinadaceae), were found in the stomach contents of one of the victims who died after taking honey thereby confirming that the deaths were due to the use of poisonous honey.

During the 1960s and 1970s, a Swiss criminalist Max Frei often used pollen as forensic evidence to link suspects to crime scenes (Palenik, 1982).

In a case, the suspect claimed that his pistol was not used in a reported murder because it was in its storage during this period. Dr. Frei examined and proved that grease on the pistol contained Alder and Birch pollens both of which were pollinating at the time of murder, not when the suspect claimed he had last cleaned the pistol and put it away (Newnax, 1984).

The forensic pollen fingerprints have been highlighted very prominently in a murder mystery called The Probable Cause (Pearson, 1992). In this paper an attempt has been made to highlight the significance of pollens in forensic problems.

Methodology

The suspected clothing and articles are to be placed on a table in a room and beaten with a stick and the dirt and dust that comes out are collected and kept in 70% ethyl alcohol. Slides can then be prepared for the presence of pollens according to Nair(1960) which is described below:

  1. Collect the fresh or suspect pollen in 70% ethyl alcohol and crush with a glass rod. Sieve the dispersion through a fine mesh, and collect it into two separate tubes (A and B) in the ratio of 1:2.
  2. Centrifuge the contents of tube A and a few drops of 1% safranin. After 5 minutes add some water and centrifuge. Discard the supernatant and add more water. Continue washing with water until the supernatant is colourless. When washing is over, add 3ml of dilute glycerine (50% glycernie in water) and keep the tube aside. Acetolysis

Centrifuge portion B, pour out alcohol and add 5 ml of glacial acetic acid. Centrifuge again and decant.

To the sediment add about 6 ml of acetolysis mixture (1 ml of concentrated sulphuric acid added drop by drop to 9 ml acetic anhydride).

Keep the tube in a water bath and heat from 70oC to boiling point. Stir with a glass-rod, centrifuge and decant waste acetolysis mixture.

Add 100 ml of glacial acetic acid and stir again. Divide the sediment in tube B into two equal portions (B and C). Centrifuge the contents of tube B; remove acetic acid.

Add water and shake well, Centrifuge again, and decant.

Add 2 ml dilute glycerin and keep tube B aside.

Chlorination

To tube C add one or two drops of saturated sodium chlorate solution in water, followed by on or two drops of concentrated hydrochloric acid.

Centrifuge and decant. Wash with water and add a few drops of methyl green.

Wash again with water till it becomes colourless.

Mounting

Transfer the pollen from tube A to tube B and then from B to tube C.

Mount pollen grains in glycerin jelly. Warm, and place a cover slip gradually. Seal with wax. When seen through the microscope, the acetolysed pollens would look brown, the untreated ones red, and chlorinated green.

DISCUSSION

The study of pollens in forensic problems has helped in solving several cases of murder, rape, etc. in New Zealand, Sweden and many other courtiers. In India, however, this important area has not received much attention. If due attention is given to this important aspect many cases of adulteration of food and other eatables such as honey, milk, etc and cases of rape, murder, kidnapping can be solved easily. Pollen evidence has also become significant in determining the manner and time of death, source of origin of illegal drugs and their route through which it has probably been transported.

Although palynology has so far been neglected, it is hoped that sooner or later, forensic palynology will be used in several crime solving exercises especially in cases of rape, bestiality, murder, illegal drug trafficking etc. when other evidence may not be available.

ACKNOWLEDGEMENT

I have to thank Professor P.K. Chattopadhyay, Director, Amity Institute of Forensic Sciences, New Delhi who suggested the present problem, and for his critical comments and encouragement.

Pollen shapes

REFERENCE

  1. Chattopadhyay,P.,K.,(2005): Personal Discussion.
  2. Coyle H., M., Ladd C., Palmbach T., Lee H.C. (2001): The Green Revolution: Botanical Contributions to Forensics and Drug Enforcement. Croatian Medical Journal 42(3): 340-345.
  3. Eyring MB, (1997): Soil pollen analysis from a forensic point of view. Microscope; 44: 81-97.
  4. Faegri, K., Iverson, J., and Krzywinski, K., (1989): Textbook of pollen analysis, 4th edition, John Willy & Sons, New York.
  5. Horrocks, M, Walsh KAJ, (1998): Forensic palynology: assessing the value of the evidence, V.A.(eds)Review of Paleobotany and Palynology, Special Issue, New Frontiers and Applications in Palynology- IX IPC.103, 69-74.
  6. Horrocks M, Walsh KAJ. (1999): Fine resolution of pollen patterns in limited space: differentiating a crime scene and alibi scene seven meters apart. J Forensic Sciences 44:417-20
  7. Horrocks, M. Coulson, S.A., Walsh, K.A.J., Forensic Palynology variation in the pollen content of soil surface samples. J.Forensic Sciences 43:320-3.
  8. Mildenhall, D.C. (1992): Pollen plays part in crime-busting. Forensic Focus, 11, pp. 1-4.
  9. Nair,PKK,(1960): A modification in the method of pollen preparation. J.Sci.Industr.Res.19C; 26-27.
  10. Petra, J.M., Greer. S., Brackel.J. Dikson, J.H Schinkel, C., Welsh R.P. Sterverus, M., Tusner, N.J., Shadow, M, and Washington R, (2005): Forensic Palynology and Ethnobotany of Salicornia species (Chenopodiaceae) in northwest Canada and Alaska. Can. J. Bot/Rev. Can Bot. 83(1): 111-123.
  11. Pearson, R., (1991) Probable Cause, St. Martin Paperbacks, New York.
  12. Stanley, E.A., (1991): Forensic Palynology, Proceedings of the International Symposium on the Forensic Aspects of Trace Evidence, USDOJ. Pp. 17-30. Stanley, E.A., (1992) Application of Palynology to establish the provenance and travel history of illicit drugs, Microscope, 40, pp. 149-152.
  13. Stephanie N., Forensic palynology: A new way to catch crooks, Forensic biology article. http://www2.bxscience .edu/publications/ forensicbio/articles/crimescene/f-crim01.htm. Szibor R, Schubert C, Schoning R, Krause D, Wendt U. (1998) Pollen analysis reveals murder season. Nature 395:449-50.
  14. Wiltshire, P., E., J., Environmental Profiling and Forensic Palynology.(Membership required) http://www.bahid.org/docs/NCF_ENv%20Prof.html.

Dr. Kapil Dev
Forensic Science Division, Amity Institute of
Behavioural, Health and Allied Sciences, Yasho
Bhavan, Okhla. New Delhi

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