Forensic Palynology: Meaning, Analysis and Problems

In this article we will discuss about: 1. Introduction to Forensic Palynology 2. Methodology in Forensic Palynology 3. Analysis, Testimony and Liability 4. Forensic Palynology as an Aid to Criminology 5. Problems.

Introduction to Forensic Palynology:

Forensic Palynology is the science of ap­plying modern and fossil pollen and spores to help solve legal problems. In its broader application, the field of forensic palynology also includes legal information de­rived from the analyses of a broad range of or­ganic walled microscopic organisms such as pollen grains, dinoflagelletes, acritarchs and chitinozoans that can be found in both fresh and marine environments.

However, in most sampling situations forensic palynologists rarely encounter these other types of acid resistant palynomorphs because most are marine and many are restricted only to fossil deposits.

It is difficult to establish precisely when the field of forensic palynology began. Attempts made prior to the 1950s, probably did not gain public attention and was therefore, not reported, or it is possible that the results may have been purposely hidden from the media so as to alert criminals about the use of this technique.

However, the first reported use of forensic palynology occurred in Sweden and Austria in 1959. The details of both the case is worth noting. The first case revolved around a woman who was killed in May, during a trip in central Sweden. During the court hearing, a number of experts including a palynologist were asked to examine the dirt attached to the women’s clothing.

The objectives of those studies were to determine whether or not the woman was killed where she was found, or if she had been killed elsewhere and then dumped at the site where the body was discovered. Preliminary studies of the pollen suggested that she had been killed elsewhere because the dirt did not have pollen from Plantago, Rumex, and grasses, which were common to the area where the body was found.

However, later reinterpretation of the forensic pollen samples noted that the murder could have occurred in May because that was before the grasses and herbs in the region had pollinated. The two opinions were both entered as evidence in the court proceedings, but it was not known if the murder was ever solved.

In the second case a man disappeared near Vienna on a journey down to Danube, but his body could not be found. A pair of muddy shoes belonging to his suspected killer was examined by palynologist Wilhelm Klaus of the University of Vienna. In the mud, Klaus found Spruce, Willow, and Alder pollen, as well as a fossil Hickory pollen grain estimated to be 20 million years old.

From these data he determined that only small area along the Danube Valley, 20km north of Vienna, contained this precise mixture of pollen. When the police confronted the defendant with these results, he confessed and showed authorities where he had buried the body in the area indicated by Klaus.

Archaeologist use these methods in determining the environmental, social and cultural conditions of primitive peoples by the study of the plant remains associated with buried bodies.

2. Methodology in Forensic Palynology:

In forensic palynology collection, extraction and techniques to identify recycled pollen and spore assemblages from samples are very critical and must be done correctly to produce accurate results.

1. Collection of potential pollen/spores forensic samples:

Ideally, forensic pollen samples should be collected by competent palynologists knowledgeable in the field of forensics. Such individuals will know how to collect contamination free samples.

They will also know what precaution should be taken to ensure that forensic pollen samples remain contamination free throughout the storage, laboratory extraction phase, and during the analysis process. If it is not possible to have samples collected by forensic paleontologists, then there are guidelines other should follow to ensure that such samples are collected properly and remain contamination free.

Three aspects should be considered while collecting samples for forensic studies:

a. What type of material should be collected;

b. How should be the materials collected and by whom;

c. How should samples be treated once they are collected?

The potential source for forensic pollen materials is infinite. Some common sources include:

a. Mud, soil and dust (sediment) from almost any surface, from car tier to clothing’s;

b. Hair from an animal, person or garment or product made from hair or fibre;

c. Packing materials;

d. Illegal drugs;

e. Stomach and intestine contents of murdered victims; and

f. Pollen trapped in a car, etc.

A brief outline of the methodology used in collecting samples from some of these sources is discussed below:

i. Sediments:

It was more than a hundred years ago that soil evidence was effectively used for criminal investigation. But it was in a fictional literature of Sherlock Holmes series written by Sir Arthur Conan Doyle.

At almost the same time Hans Gross of Austria wrote in his Handbook for criminalistics that dirt on shoes probably can tell useful information for criminal investigation, but it did not include any actual case study in which soil could be physical evidence. According to the report by Murray George Pop of Germany might be the first scientist who examined soil evidence and led the solution of the murder case in 1904.

Microscopically, soil is heterogenous mixture consist of organic matter, rock fragments, mineral grains, clay, oxides etc. Therefore unique particles can be of important to characterize soil evidence. A small crumb is much more important, and bulk analysis frequently gives poor results for forensic soil examination.

Some particular fractions of soil can be useful for forensic soil discrimination rather than the bulk analysis. Some analytical methods such as x-ray fluorescence spectrometric analysis of free oxides, high performance liquid chromatographic analysis of polycyclic aromatic hydrocarbons had been proposed.

Recently several interesting articles have been published that describes the importance of soil evidence and contribution of geologists to criminal investigation, with many historical case studies.

Soil evidence further can contribute to drug intelligence development for instance, soil taken from containers, ships, or trucks is useful to identify drug shipment pathway. Using air photo, satellite imagery enabled to locate underground bunkers, which were built to grow Cannabis by map interpretation techniques.

Forensic soil examination has been believed to be very complicated because of complexity of soil, but such diversity and complexity enable us to discriminate soil samples with high discriminating power. The biggest problem in forensic soil examination is shortage of well- trained staffs and expertise for soil in crime laboratories.

Soil, dirt and dust are common elements at almost every crime scene. As such they should be collected carefully as these elements often contain abundant pollen and spore.

Samples of dirt collected from the clothing, skin, shoes or the car of a victim might prove useful in linking the victim with the location where the crime occurred. Mud found on a stolen vehicle or a vehicle used in a crime, could link the vehicle with the scene of crime or link it to the place from where it was stolen.

Dirt found associated with other objects or other type of conveyances, like bicycle, motorcycle, boat, etc., thought to be associated with a crime also might yield pollen evidence useful in linking those items with a specific crime or a specific geographic location.

The following procedural methods are used while collecting the samples:

i) If dirt and mud have dried on objects, a soft, clean, paint brush should be used to clean the surface before collection. It has been found that soft, sable hair brushes designed for applying cosmetic facial rouge are best suited for this type of work. This procedure will remove possible surface contamination of ambient pollen that may have settled on the dirt or mud sample after it dried.

The paint brush used must be cleaned and free of pollen. This can be achieved by thoroughly washing it with a mixture of distilled water and detergent and rinsing it first with distilled water and then alcohol prior to using. There must be supply of spare brushes each in a separate sterile sealed plastic bag.

ii) Once the dirt or the mud is cleaned, the collector should wear a clean pair of sterile surgical gloves while collecting each sample. Actual collection should consist of picking of the dirt or mud fragments or gently scrapping them with a clean implement. The size of the sample collected will vary.

Small sample is easier to protect from possible contamination, yet the smaller the samples the more difficult it will be for the palynologists to extract sufficient number of pollen or spores for analysis. If there is any doubt, it is wiser to collect a bit more sample then it is needed.

iii) After collection, each sample should be placed in a sterile, plastic bag and tightly sealed. This will ensure that no pollen contamination occurs between the time of collection and the laboratory analysis of the sample.

The use of plastic bag has two potential draw backs:

a) If a sample of dirt, mud or other material is moist it will not dry properly if sealed in a plastic bag. Thus the bag should be sealed when the sample is collected and later opened slightly, and carefully placed in an oven at low heat until the sample is dry. The other alternative is to add sufficient alcohol to the sample to kill any microbes that might cause damage to the pollen in the sample.

b) In dry atmosphere it might be difficult to get dust into a plastic bag full of static electricity. In that case the dust can be placed on to a clean, paper envelope. Next the envelope is sealed and placed in a sealed plastic bag.

iv) In cases where there is not enough dust to sweep into some type of container, then one should try collecting pollen samples using transparent cellophane tape. A role of one inch wide cellophane tape is ideal. Using sterile gloves, one should tear off long pieces of tape and stick them on the surface to be sampled. Next the tape is removed carefully, with the dust attached, and sticks it together; one half stuck on the other half.

This protects the sampling surface of the tape and prevents further contamination of the once sticky surfaces. After the completion of the sampling each tape is placed separately in sterile, zip-lock plastic bags to prevent potential contamination of the sample. In the laboratory solvents are used to loosen the material stuck to the tape.

ii. Hair:

Hair is an excellent pollen trap. When wind blows through hair, pollen in the wind becomes trapped in the open space between individual strands. In humans, the addition of various types of hair spray and tonic makes hair surface sticky and provides an even better trap for pollen. Hair can be sampled for its pollen contents by carefully washing with detergents and warm distilled water. This will loosen trapped pollen and free it from sticky hair surfaces.

Once collected the wash water must be stored in a sterile container that is tightly closed and frozen or kept at a temperature near freezing in a refrigerator which retard microbe growth.

If refrigeration is not possible then it can be alternatively stored in alcohol, to prevent growth of fungi and bacteria. Hair sampling may not be restricted to human hairs only, as rugs found at the scene of a crime might have been used to wipe shoes and thus may be rich in pollen.

Cattle, sheep, or other stolen fur bearing animals might be traced to their original owner through the pollen analysis of hair samples washed or shaved from their bodies.

Hair or fur coats, blankets, felt hats, or sheep skins sometimes used as a car seat cover all act as excellent pollen traps, and should be considered for their potential forensic value. Each of these samples should be placed in a sterile, plastic bag that is sealed and remains unopened until it can be analysed.

iii. Woven bags, cloths, ropes, baskets and clothing:

Woven cloths or bags have the same trapping properties as the hair. Pollen in the atmosphere is constantly settling on exposed surface. Woven material left exposed to the air becomes coated with air borne pollen that is trapped in the fibers of the material. Woven cloth bags or burlap used to transport products become exposed to the pollen rain of the region where their contents are being produced and packed.

Thus, coffee beans packaged in burlap bags in Costa Rica will contain a pollen assemblage from those regions. If there is a problem in placing the whole item in a sterile plastic bag and then sealed, then each item should be repeatedly sampled using pieces of transparent cellophane tape. The same procedure is followed as explained for sampling dust.

Baskets used to transport products, often contain pollen grains trapped in spaces between their weave. These trapped pollen types are often indicative of the place where the baskets were made. Similarly products stored in the baskets, i.e., marijuana, tea, coca, coffee beans, etc., often contain pollen that will become trapped in the basket’s weave. Like baskets and woven bags, the weaving of clothing also becomes a natural trap for ambient pollen.

This is truer for coarse weave garments made of burlap, cotton, or wool where the coarse fibers act as natural traps. While sampling for pollen trapped in woven bags, baskets, or items of clothing, the item should be placed in a large sterile, plastic bag and sealed.

Later, in the laboratory forensic palynologists can remove the pollen from these items by thoroughly rinsing them in a solution of hot, soapy, distilled water. The process will dislodge the trapped pollen, and once removed, the wash solution should be processed for its pollen contents or freeze until it can be processed.

iv. Packing materials:

Several products are packaged with various types of packing materials. In case where products are packaged outdoors, or in open – air ware house, ambient pollen can enter the packaging area and settle on the packaging material being used. Later, a pollen analysis of these materials may reveal clues about the locality where certain products were produced or packaged.

Portable vacuum cleaner is effective tools for collecting pollen from packaging materials. The advantage of the vacuum cleaner is that it can clean a large area quickly and the suction it generates will dislodge most trapped pollen and suck it into the vacuum cleaner’s lint trap.

Before using this technique it is important that the vacuum cleaner is thoroughly cleaned and a sterile lint bag is used. Fibreglass or paper filter bags are preferred, as they quickly dissolve in certain acids yet leaving the collected pollen undamaged.

v. Illegal drugs:

The most useful application of forensic pollen samples is in the search for, and identification of, illegal drugs. It is often important to link specific individuals with specific shipments of illegal drugs, determine if drugs found in various localities are part of the same original shipment, or it may be important to trace and identify shipments of drugs coming from a specific processing laboratory or a specific geographical region.

Marijuana plants (Cannabis sativa) are one of the nature’s most prolific pollen producers. Its packaging often occurs in the open, thus large amount of Marijuana pollen and other pollen from local pollen rain, will become incorporated as part of the material being packaged.

On the other hand, if Marijuana plants are grown, harvested, processed, and shipped from locations that are entirely indoors, then few local pollen rains may become incorporated in the harvested product.

This makes it difficult to determine the precise geographical location where the plants were being grown or processed. In the process of turning Coca leaves into Cocaine the leaves of the Coca plants are picked, dried in the open, processed in outdoor areas, and then refined into cocaine.

Since most of these occur in, or near, the place where Coca leaves are grown, pollen from other plants in the area should be reflected in samples of the refined cocaine. Similarly the first step in the production of heroin, the outer surface of the immature seed pod is scared. This scaring produces a sticky sap that becomes an excellent pollen trap until it dries.

Baskets, bags, packing materials, vehicles, the clothing of individuals, and even the paper money associated with drug transactions are potential source for collecting samples for pollen studies. The resulting pollen information’s from each such study could link individuals or items with illegal drug shipments, can determine whether or not several shipments have a different or common geographical origin where the drug was made or processed.

vi. Stomach and intestine:

When a victim has been killed, forensic pollen samples should be collected from the stomach, small intestine, and colon area during an autopsy If victims remain have been severely decomposed or the victim was buried and only skeletal materials remains, forensic pollen samples should still be collected.

In burials thin layer of soil in actual contact with the underside of skeletal bones in the chest and pelvic regions should be collected. These samples might provide clues as to the time of the year when the victim was buried or could contain pollen that had been on victim’s clothing at the time of the death. Samples of dirt should also be collected from the region inside the pelvic area because these samples may reveal clues about the victim’s diet and possibly where he lived.

Different studies have revealed that several types of pollen remain trapped in human digestive tract for different periods of time. Brassica (Broccoli) pollen is very small and has a reticulate type of surface ornamentation, a factor that permits it to become easily trapped in the folds of the stomach and intestine.

Prosopis (Mesquite) pollen, is large, football shaped and with a smooth surface, a factor that speed its movement through the human digestive tract. It has been experimentally tested that after eating a meal that includes broccoli, there will be an initial high concentration of Brassica pollen in the feces of that person about two days later.

After that, the percentage of the said pollen continues to remain high for another week or so before it begins to decline. Test show that traces of Brassica pollen are still detectable in feces after a month following initial ingestion. On the other hand there is an initial rise in mesquite pollen in the feces produced 2-3 days after initial ingestion, but all traces of this pollen type disappears after about eight days.

Sample collection should be done with the same degree of care as mentioned earlier. As stated earlier that ambient pollen is constantly settling out of the atmosphere. Therefore, it is possible that some of those pollen grains may have settled on foods and drinks consumed by the victim. If so, the pollen trapped in the stomach and intestine may provide clues about where the individual had been just prior to death.

The other kinds of materials suitable for forensic study are:

a) Honey- to verify the supposed floral source and specific geographical localities.

b) Dried fruits- imported Apricots, Prunes, or Raisins to determine their country of origin.

c) Tea- to determine its country of origin.

d) Raw sugar- to authenticate its geographical origin.

e) Coffee- to evaluate the country of origin by examining pollen trapped in the weave of burlap bags used to package the coffee beans.

f) Sisal- to confirm the imported sisal rope actually comes from the purported country of origin.

g) Coins and Paper money- to validate if ancient coins or paper money are from their country of origin or are fakes, or in some cases it has been in contact with Marijuana pollen.

h) Tobacco- to determine whether is it of foreign or domestic origin.

i) Antique furniture- to confirm the possible age and origin of antique furniture supposed to come from a specific geographical location.

j) Air filters- to indicate localities where private airplane, trucks or cars have visited.

2. Laboratory techniques:

i. Collection of control samples:

It is essential to collect ‘Control Samples’ that reflect the normal pollen rain and come from soil or dust of a region where a crime was believed to have been committed. The pollen spectra in the control samples, form ‘baselines’ of data, against which to compare forensic samples.

An example of why control samples are important is illustrated by the following. If a crime is committed in a wooded locale where the dominant plants are Alder, Birch, Maple, and Pine, then control samples of surface dirt collected from that region should reveal a pollen record containing various percentage of those major pollen types and traces of other minor pollen components.

Later, if the muddy shoes of a suspect or mud from a suspect’s car is collected and examined, then the pollen assemblage in those forensic samples might match the pollen assemblage found in the control samples.

However, without knowing what pollen types, and in what percentage, one should expect to find at the scene of the crime, it is difficult to argue in court that pollen found in the suspect’s shoe, or car, actually link the person with the scene of the crime.

The following criteria should be considered while collecting control samples:

i) Control samples should be collected as close to the exact spot where a crime had occurred.

ii) Additional control samples should be collected from the areas near the scene of the crime. If the surrounding area within one kilometer radius consists of similar vegetation, then one or two control samples from each of the four cardinal directions, about 500 meter away from the scene of crime, should be sufficient. If the area within one kilometer radius contains different types of vegetation, i.e., agricultural fields, open grass lands, wooded areas, etc., then two control samples should be collected from each vegetation zone.

The ideal way to collect control samples is to use the “Pinch” method. This is done by selecting an area about 50 to 100 meters square and walking back and forth collecting pinches of dirt throughout the area. Each pinch of dirt is combined into a single, sterile, plastic bag and then sealed. This idea of combining all pinches of dirt is to prevent the possibility of over- representation of a single pollen type. Test using pinch method reveal that in most cases more than eight pinches of dirt are needed for each control sample before their combined dirt yields a reliable pollen assemblage of the regional flora.

Generally, collection of 10 to 20 pinches of dirt per control sampling locations is sufficient to ensure an accurate sample. As usual with the collection of forensic samples one should wear gloves or wash one’s hands with detergent prior to, and between, collecting each control sample.

ii. Extraction of samples:

Extraction is an important part of forensic pollen study, and should be conducted by competent forensic palynologists. The palynologist’s previous experience, professional reputation, and the facilities available in the laboratory are important factors to be considered. A forensic pollen laboratory should be contamination free and should be tested at regular intervals to ensure it remains free of ambient pollen and spore contamination.

All glass wares and other equipment’s should be thoroughly cleaned and only distilled water should be used for each stage of the extraction procedure. Extraction procedure should ensure the maximum recovery of pollen and the minimal chance of pollen loss should be attempted. In certain cases initial checks should be conducted using staining or wet mounts to determine if any of the pollen or spores still has an intine or cytoplasm. These criteria are sometimes used to determine fresh from fossil pollen.

Written records should be kept for extraction process and precise notations for procedures. It must be remembered that each step of an extraction process and each observation may need to be justified, explained, and defined in a court of law.

The extraction procedure involves:

a) If there is ample material, normal extraction procedures utilizing standard procedures such as acetolysis, Schulze solution, nitric acid, hydrofluoric acid, heavy density separation, and other techniques work well.

b) In case of sample, extraction work should be done in a very small, micro-sized, conical shaped glass tubes (1-5 ml.) or in the concave depression of a hanging-drop, glass slide. All processes, even acetolysis can be completed in the depression of a hanging-drop slide.

c) In case where cellophane tape has been used to collect forensic pollen samples it can be stuck to a microscope slide, stained and examined without any further processing. Sometimes it may be necessary to remove the pollen from the cellophane tape and then process the removed material in a micro-sized test tube.

iii. Technique to identify recycled pollen:

There are several techniques used to identify recycled pollen in standard samples, and these include:

a) Staining with basic Fuchsin and then noting which grains contained an intine, and which did not. Those that still had an intine were counted as being part of the recent pollen rain, and those that did not were considered recycled pollen.

b) Fluorescence has also been used with some success to recognize which pollen grains are recycled and which are not. Pollen grains and other types of organic materials in different stages of preservation will emit light of varying intensity and wavelengths. These differences can be detected under ultraviolet light during fluorescence studies and make the different pollen grains appear as different colour hues.

In laboratory experiment conducted at the Texas A & M Palynology Laboratory “spikes” of modern pollen and spores were added to pollen samples of known age collected from the Boriack peat bog. After processing and counting the pollen in each peat samples, modern pollen and spore spikes were added to other pet samples from the same core samples and then processed.

Palynologists who did not know which type of modern pollen then counted prepared pollen slides and spores had been added to the fossil samples. The results of the count demonstrated that for the peat samples that ranged in age from 2000 to 15000 years old, added pollen be recognized using fluorescence.

3. Analysis, Testimony and Liability of Forensic Palynology:

These three form an integral part of the forensic palynology:

1. Analysis:

The basic concern in forensic study is the potential for misidentification of pollen and the subsequent misinterpretation of the evidence. There are million of species of pollen and spore producing plants in the world. Single palynologists cannot become an authority on all pollen and spore types and rarely does a pollen laboratory have modern pollen reference collections containing more than a few thousands pollen and spore taxa.

Moreover, it’s quite unusual for palynologists to have a working knowledge of the precise pollen flora or pollen assemblages typically found in more than a few regions of the world. This is why forensic palynologists often present results in terms of probable rather than precise certainty when discussing some samples.

2. Testimony:

Most pollen results and interpretations are circumstantial rather than precise. Its usefulness is based on its ability to associate, or object, with the scene of a crime and by the implication show the suspect, or object, may have been involved in the crime. This one of the reasons pollen data have not been utilized more widely as evidence in court.

While reporting the results of forensic samples, a palynologist might say the pollen evidence probably indicates a specific geographical locale. However, under cross examination the palynologists might have to admit that without extensive testing of many control samples, it is impossible to state, beyond doubt, that a specific pollen assemblage is absolutely unique.

It is always possible that some other locality or some other region, with similar floral components, might also have a similar pollen assemblage. Pollen assemblage is not like DNA finger printing where one might be able to state the probability of two samples being identical one in a million or more.

Although each pollen assemblage is unique in its own way, it is difficult to illustrate this point without using complex mathematical calculations, conducting additional time consuming analysis of many pollen control samples, and relaying on computer generated programs to show statistical probability. These points should be mentioned and explained in court, but the strength of the pollen evidence should focus in its ability to provide a higher than average probability.

3. Liability:

One aspect of working with forensic samples in most countries is the possibility of being sued as a result of presenting testimony in court. All forensic palynologists should seek legal advice on personal liability from their own state or federal court system. They should also obtain a clear understanding of their potential liability from the agency for whom they are working.

In this way all parties will understand the degree of liability involved in the release of the forensic evidence and will what to expect as result of testifying in court. There is one more liability that occasionally occurs when testifying as a forensic palynologist. A convicted defendant may become so enraged that he or she will threaten the forensic palynologists with harm.

4. Forensic Palynology as an Aid to Criminology:

The palynology laboratory at Texas A & M University and Institute of Geological and Nuclear Science, New Zealand are the two places where forensic pollen studies are conducted on a routine basis. New Zealand is the world’s leading country to use of forensic palynology.

The following examples from actual cases where forensic palynology was used successfully to provide vital information in a civil or criminal suit are listed in some of the case study listed below:

1. Evidence from sediments:

Case 1:

In New Zealand a batch of women were taking a stroll along an isolated beach. They were insisted by few men to join them in the walk inspite of their repeated reluctance to leave them alone. A motorist later saw a lady walking down a muddy road leading to a nearest highway. Her dresses were torn and soiled and she was in a confused state of mind.

The motorist then took her to the nearest police station where she recorded the entire episode. In her statement she narrated that after leaving her girlfriends to a nearby place she continued her walk along the beach. It was then that she was assaulted and sexually harassed by one of the man who was troubling them earlier in the afternoon.

The very next day the investigation team arrested a possible suspect from the nearby area who was identified by the women in police line­up. Police were confident in their arrest but it needed evidence to hold him in the jail. The situation was further complicated by the statement of his friends.

They testified that their friend as suspected by the police could not have been in the beach when the assault had occurred since he was with them for the whole day and they had not been to the beach. Police had no other alternative then to conduct a search of his apartment that exposed a pair of sneakers, which were neatly cleaned.

However, a small amount of mud was left out which proved a vital source material for palynological analysis. The pollen and spores obtained from the laboratory analysis revealed the flora of the beach dunes where the assault had taken place. This no doubt linked the suspect to the beach but not to the precise site where the assault had occurred.

Further analysis of the mud led to the identification of shallow water dinoflagellate cysts, which incidentally was common only in the tidal floods along the beach where the assault had occurred. Thus the precise site of the assault was established. The suspect later admitted to have committed the crime at the said locality.

Case 2:

Pollen grains found on a person’s t- shirt and jeans helped to place him at the scene of an Auckland abduction and rape. Dr. Dallas Mildenhall of the Institute of Geology and Nuclear Sciences in Wellington did the scientific work on the pollen from Robert Alexander Low’s (the suspect) clothes.

A woman was raped in the early hours of New Years day in a lane leading past a church house. Artemisia, a daisy native to the Northern Hemisphere was planted along the lane to beautify the place. In the course of the assault the victim and the assailant rolled on the ground and damaged few of the shrubs some of which were in the flowering state.

Mildenhall (1990) analyzed a control sample of the soil from underneath the damaged bushes, and recorded 64 percent Artemisia pollen. The dirt smudges on the both the garments of the assailant were examined. The dirt from the jeans contained 39 percent Artemisia pollen and 27 percent unidentified pollen while the t-shirt recorded 29 percent Artemisia and five percent of the unidentified pollen.

These percentages cannot be due to an accidental brushing against the plants, thus a prolonged contact must have been made. Any one walking along the lane will not have more than a trace amount of either of the pollen types. Thus there is every possibility of the assailant having got the pollen on his clothing due to direct contact with the plant.

At the Auckland High Court trial Mildenhall expert evidence showed that Low had at the scene and that he had been in prolonged contact with the Artemisia bushes. Later Low accepted his crime for detaining the victim without consent and abusing her sexually.

Case 3:

A suspect was arrested upon arrival at a car park and a police dog traced his route back to cannabis plantation in native cut-over bush. The suspect was carrying a soil pH testing kit and small native shrub (Pseudopanax).The police maintained that the suspect had been tending a cannabis plantation.

The suspect, however, maintained that he had been looking for a native shrub to plant in his home garden. Pollen analysis was done on the soil testing kit which still had soil attached to it; on a sample from the cannabis plantation and on material from around the roots of the Pseudopanax.

The pollen from the soil testing kit and the cannabis plantation were similar; that from around the roots of the Pseudopanax was quite different. Soil from the Pseudopanax was dominated by Myrtaceae (Metrosideros; Leptospermum; Kunzea) which was rare in the other two samples.

The sample from the cannabis plantation and soil testing kit both contained cannabis pollen and both were dominated by the native Dacrydium cupressinum and grass pollen and Cythea spores. The pollen evidence later proved instrumental in obtaining a conviction.

2. Evidence from cloths and hair:

Case 1:

In a city park of New Zealand a jogging women was kidnapped at knife-point and then assaulted and killed in a nearby wooded area. Just before the disappearance of the women a man was seen walking near the jogging area. Investigating team questioned the man who confessed of being in the park but did not see the victim and had never been in the woods where the crime was committed.

Police was however not convinced by his statement and made a search of his apartment that led them to find a dark woolen sweater and a pair of soiled pants. These were sent for forensic analysis and the result showed a slightly different assemblage of pollen and spores. However, both the garments were rich in pine pollen and fern spores.

The surface soil from the crime scene was also analyzed for pollen and spores which, incidentally also recorded a high content of both pine pollen and fern spores. This concentration and type nearly tallied with the palynomorphs analyzed from the soiled shorts of the murdered women. Thus the forensic pollen ‘finger print’ of the woman’s short was nearly identical to the pollen ‘finger print’ obtained from the assailants sweater and soiled pants.

All the three palynological evidences were coherent and disclosed the fact that the only way for such a high concentration of pollen and spores on the victim’s and assailant’s garments might be due to rolling around on the ground.

Further there was no other area where pine and ferns grew together as recorded from the area of the crime. Thus the pollen ‘finger print’ of the wooded area definitely associates the suspect to the crime scene. Later it ultimately led to conviction by the suspect.

Case 2:

A farmer from America was first kidnapped, and then robbed and murdered. The farmer’s car was stolen and later dumped as it got stuck up in the mud near a busy highway. The next day a vagabond was arrested from a nearby town for breaking in to a closed liquor store.

In the prison awaiting trail, the vagabond told to one his fellow prisoner that if his car had not gotten stuck up in the mud, 30 miles south of the town then he would not have been in the jail today. The fellow prisoner with the hope of reduced punishment narrated the vagabond’s story to the Sheriff.

Later inspite of intensive questioning by the investigators, the vagabond did not provide any clue that could link him to the crime. In course of routine investigation it was noticed, that there was a large corn field between the muddy road where the stolen car had been discarded and the nearby highway leading to the next town.

This prompted the investigators to send the dirt samples collected from vagabond’s shirt and pants which were removed and stored at the time of his arrest. Interestingly the data revealed that both the garments were covered with fresh corn pollen and higher concentration was recorded from neck and shoulder region of the shirt. The palynological results clearly pointed to the fact that the vagabond had recently walked through corn field that was similar to the one located between the abandoned car and the high way.

Thus palynological evidences along with several eye witnesses of neighbours who had seen the vagabond near the highway where the car had been dumped confirmed beyond doubt that the vagabond had been in the area where the crime was committed. During the course of trial several other evidences along With the finger prints from the crime scene unambiguously linked the vagabond to the murder of the farmer.

Case 3:

A very high profile case related to the claim, that the Shroud of Turin was used to wrap the body of Christ before his burial was solved with the help of palynological data. Max Frei who went into detail investigation as to the origin of the Shroud, recorded 49 different taxa of pollen grains trapped in the fibers of the cloth. The pollen spectrum thus obtained was similar to regions of Israel and Western Mediterranean.

Some of the pollen grains were from plants with xeric habitats and represent plants that still grow in the Israel. Few pollen grains were from plants that are still found in Turkey and other additional types represented plants common to the Western Mediterranean. Beach pollen found mostly in central Europe was also found on the Shroud.

Max Frei concluded from his study that majority of the pollen grains recovered from the Shroud were from plants that are common to regions in Israel, nearby Western Mediterranean and Turkey. The European pollen taxa were possibly deposited during its display in Europe.

3. Evidence from illegal drugs:

Case 1:

In New York City the excise enforcement officials confiscated a shipment of 500 g of cocaine hydrochloride. In order to establish the origin and the voyage route the cocaine was sent for palynological investigation.

Interestingly the sample revealed three different types of pollen assemblages, viz.:

a) One assemblage that represented tropical plants now growing in the regions of Bolivia and Columbia. These grains were mixed with the samples when coca leaves were being picked and then processed to form coca paste.

b) The second assemblage consisted of pollen from Pinus banksiana (Jack pine) and Tsuga candensis (Canadian Hemlock tree). Since these two trees commonly grow in few regions of North America, it may be assumed that after the arrival of the cocaine in the United States, they must have been cut and then packaged in any one of the three places, viz., Northern Michigan or Wisconsin; in the mountains along the Canadian border of Northern New York; or in the mountain regions of New Hampshire and Maine.

c) The third pollen assemblage came from weedy plants that generally grow in barren places in New York City and Manhattan Island.

The enforcement officials concluded that the cocaine originated and processed in South America. It was then smuggled in some northern areas of United States, where it presumably cut and packaged. From there it was sent to New York City where it was possibly cut again and was being prepared for distillation, when it was apprehended.

Case 2:

In United States a person was arrested for possessing a large quantity of marijuana. The excise officials wanted to know whether the drug had a locally grown source or it was imported. In case of an import consignment it might have been a part of a large shipment linked to an organized criminal syndicate.

Palynological analysis of the marijuana samples revealed an assemblage of pollen grains and spores that resembled the flora from where the suspect was arrested. It was thus established that the marijuana had a local source, possibly home grown.

4. Miscellaneous application:

Case 1:

Scotch whisky known for its flavour and taste was shipped from the manufacturer to an importer. Surprisingly on arrival, the consignment contained only limestone rocks and there were rumors that the whisky had been illegally removed by the local port workers.

The importer was in a difficult situation to establish the fact that whether this illegal removable happened in the country from where it originated or it was replaced after it had arrived at the destination country. Such an ambiguity was due to the presence of limestone in both the countries.

To establish the source county of the rocks the importer went for micro fossil analysis of the limestones from both the countries. On examination several types of palynomorphs, especially dinoflagellates and acritarchs were recorded. A comparison of palynomorphs revealed that this illegal removable happened in the country where the whisky had been produced. Thus they were removed before their shipment and not after it reached its importer.

Case 2:

The office of the United States Inspector General became suspicious that some of the honey purchased by the United States Department of Agriculture (USDA) under the Federal subsidy programme did not meet the required domestic standards. To qualify for participation in the United States honey subsidy programme, the honey must be produced in the United States. Sample collected from USDA purchased honey was sent to forensic palynologists for analysis.

The pollen assemblage from most of the 75 honey samples examined matched expected pollen frequency found in a number of different geographical localities within the United States. However, six percent of the examined samples contained tropical pollen types common to major honey producing region in Yucatan, Mexico, rather than the United States.

Case 3:

In Arizona a bee-keeper placed his bee-hives in a blooming field of alfa alfa. Within a few weeks all the bees in each hive were dead. The bee keeper believed his bees had been poisoned by aerial insecticides that drifted in to the alfa alfa field while the nearby cotton field was sprayed.

The bee keeper sued the cotton farmer and crop duster for damages. The defendant filled a counter suit claiming that the bees had not died from aerial spraying, but instead had died from foraging on contaminated nectar and pollen in the sprayed cotton fields. If true, they claimed it was the bee’s fault, not theirs, for which they died.

Chemical and forensic pollen analysis was conducted in an effort to determine which was correct. A forensic palynologist was hired as a consultant to examine a number of dead bees recovered from the alfa alfa field. His study revealed that bees were covered with pollen from a number of different nectar plants that grew near the hives as well as cotton fields.

The pollen data, combined with chemical tests, indicated that bees had most probably died from foraging on blooms in the contaminated cotton field. Thus, the death of the bees was determined to be an indirect result, not a direct, from the aerial spraying.

5. Problems of Forensic Palynology:

The full potential of forensic palynology remains untapped and ignored in most countries, except New Zealand, where forensic palynology is widely accepted and routinely used to gather evidence in civil and criminal cases.

There are four basic reasons why forensic palynology is not being widely used, these include:

1. Availability of specialists:

If the law enforcement authorities want to use forensic palynology, they might have a problem in finding pollen analyst with a forensic experience or who is trained in the techniques of forensic palynology.

One primary concern, in some countries such as United States, is personal liability if asked to testify in court. A second concern is the potential of having to submit to cross-examination in court.

Such cross-examination can be a devastating experience for a scientist who may not be accustomed to having his or her personal life, education, research methods, or scientific expertise drawn into question. Also of concern is the time needed to research the background and conduct forensic analysis and how the work might interfere with other types of pollen research the palynologist already has under investigation.

2. Sample collection:

It remains a major problem. Forensic pollen samples collected improperly or contaminated after collection are of minimal value to the forensic palynologists. This is why the law enforcement agencies seek the advice of skilled forensic palynologists before as well as after forensic samples is collected.

No forensic palynologist wants to waste time examining samples and conducting analysis of materials that later prove to be of little value because of improper collection or conta­mination.

3. Availability of facilities:

Many palynologists may not be equipped to conduct forensic work. Contamination free- laboratory facilities equipped with special types of equipment needed in processing samples may be lacking.

Further, because there are generally hundreds or thousands of potential plant taxa that could exist in any given environment, each of which could be a potential pollen or spore contributor to the pollen assemblage. Precise identification of all taxa in a forensic pollen sample is often time consuming.

Unknown pollen and spore types must be checked against reference collections and taxonomic keys. Not all palynologists have collections that encompass a broad range of pollen types found in many different regions of the world. Finally, not all palynologists have access to scanning electron microscopes which in some critical circumstances are needed to determine precise identification.

4. Availability of financial support:

Funding for forensic work may sometimes be a major concern. Like any other type of pollen research, funds are needed to pay for expendable supplies, replenish laboratory chemicals, and for the time spent by a forensic laboratory technician and the pollen analyst.

Although some forensic palynologists are employed by state, provincial, or federal agencies, and may be able to conduct a few forensic studies free of charge, but most cannot. This concept of users being asked to pay for pollen analysis is not something that all law enforcement personnel accept.

Conclusion:

It is popularly said that “it just takes few specks of dust and you are caught”. The science is still in its infancy and remains untried in many parts of the world. Forensic samples can well be regarded as a tool to convict a suspect or at times can point investigations in the right direction, thus narrowing the number of suspects. Though as a supportive role, forensic palynology can become a powerful tool of the forensic scientists.