Mycology in palaeoecology and forensic science.

Palynology (including mycology) is widely used in palaeoecological and bioarchaeological studies. Lake and mire sediments, soils, and the deposits accumulating in archaeological features, invariably contain plant and fungal remains, particularly pollen and spores. These serve as proxy indicators of ancient environmental conditions and events. Forensic palynology has been successfully employed in criminal investigations for more than two decades. In recent years, it has included fungal palynomorphs in profiling samples from crime scenes, and from exhibits obtained from suspects and victims. This contribution outlines the main features of palynology, and gives examples of case studies where fungal spores, pollen, and plant spores, have enhanced the interpretation of ancient landscapes and land-use, and provided pivotal intelligence, and probative evidence, in criminal investigations.

Rarely reported fungal spores and structures: An overlooked source of probative trace evidence in criminal investigations.

The value of pollen and plant spores as trace evidence has long been established, but it is only in the last eight years that fungal spores have been analysed routinely from the same palynological samples. They have greatly enhanced the specificity of links between people, objects, and places. Most fungal species occupy restricted ecological niches and their distributions can be limited both spatially and geographically. Spores may be dispersed over very short distances from the fungal sporophore,(1) and their presence in any palynological assemblage may indicate a restricted area of ground, or the presence of particular plants (even specific dead plant material). Fungal spores can represent primary, secondary, or even tertiary proxy evidence of a location, and can indicate the presence of a plant even though the plant is not obvious at a crime scene. In some cases, spores from fungi which have rarely been reported, and are considered to be rare, have been of particular value in providing intelligence or evidence of contact. Ten examples are given from case work in which rarely reported or unusual fungi have proved to be important in criminal investigations.

Light microscopy can reveal the consumption of a mixture of psychotropic plant and fungal material in suspicious death.

Light microscopical examination of plant and fungal remains in the post mortem gut may be capable of demonstrating the ingestion of unexpected natural psychotropic materials. This is demonstrated here in a case in which a 'shaman' was accused of causing the death of a young man. The deceased had participated in a ceremony which involved the drinking of ayahuasca in order to induce a psychotropic experience. Ayahuasca is an infusion of Banisteriopsis caapi (ayahuasca vine), which produces a monoamine oxidase inhibitor, and one or more additional tropical plants, generally Psychotria viridis (chacruna) which produces dimethyltryptamine (DMT). The monoamine oxidase inhibitor prevents DMT from being broken down in the gut, so enabling its passage into the bloodstream and across the blood/brain barrier. Toxicological tests for DMT demonstrated the presence of this compound in the body. The deceased was reported to be in the habit of using Psilocybe semilanceata (liberty cap). This fungus (popularly called magic mushroom) contains psilocybin which is hydrolysed in the gut to psilocin; this compound mimics a serotonin uptake inhibitor, and also invokes psychotropic experiences. Microscopical examination established that the ileum and colon contained spores of Psilocybe and, in addition, pollen of Cannabis sativa and seeds of Papaver cf. somniferum (opium poppy). Both the plant species yield psychotropic substances. Palynological and mycological analysis of containers from the deceased person's dwelling also yielded abundant trace evidence of pertinent pollen and spores. The police had requested analysis for DMT but there was no screening for other psychotropic substances. Investigators were surprised that a mixture of hallucinogenic materials had been consumed by the deceased. The charge was modified from manslaughter to possession of a 'Class A' drug as the deceased had been consuming psychotropic substances not administered by the 'shaman'. Where death involving drugs from plants or fungi is suspected, microscopical examination of samples from the gut can provide a rapid and effective method for assessing, in a temporal context, the presence of ingested materials that may not have been previously suspected. The example presented here also demonstrates the need for caution in interpreting toxicological results where screening for unusual compounds has been limited.

Two sources and two kinds of trace evidence: Enhancing the links between clothing, footwear and crime scene.

The body of a murdered woman was found on the planted periphery of a busy roundabout in Dundee, United Kingdom. A suspect was apprehended and his footwear yielded a similar palynological (botanical and mycological) profile to that obtained from the ground and vegetation of the crime scene, and to that of the victim's clothing. The sources of palynomorphs at the roundabout were the in situ vegetation, and macerated woody mulch which had been laid on the ground surface. The degree of rarity of individual forensic markers, the complexity of the overall profile, and the application of both botanical and mycological expertise, led to a high level of resolution in the results, enabling the exhibits to be linked to the crime scene. The suspect was convicted of murder. The interpretation of the results allowed conclusions which added to the list of essential protocols for crime scene sampling as well the requirement for advanced expertise in identification.

A Rapid and Efficient Method for Evaluation of Suspect Testimony: Palynological Scanning.

A rapid method for evaluating suspect testimony is valuable at any stage in an inquiry and can result in a change of direction in an investigation. Rape cases, in particular, can present problems where a defendant renders DNA analysis redundant by claiming that the claimant consented to have sexual relations. Forensic palynology is valuable in confirming or eliminating locations as being crime scenes, thus checking the testimony of both parties. In contrast to some forensic disciplines, forensic palynology can provide critical information without time-consuming full analysis. Two cases are described where the palynological assemblages from comparator samples of pertinent places were compared with those obtained from clothing of claimants and defendants. The results of rapid microscopical scanning of relevant preparations led to early confessions, thus obviating the need for costly analyses and protracted court proceedings. A third case demonstrates the unbiased nature of this technique where a man, although innocent of any offense, lied about having visited the crime scene for fear of prosecution. This highlights the need for sensitive policing in claims of rape.

Palynology and mycology provide separate classes of probative evidence from the same forensic samples: a rape case from southern England.

A young woman claimed to have been raped at night in a wooded strip of land 120 m from her home. The suspect refuted her claim and said that they had had consensual sexual relations on an area of short turf in a local park, 130 m distant from the alleged crime scene. Comparator samples from each place, and clothing and footwear from each party, were obtained for assessment and analysis. All places that were considered to be relevant to the case were visited, and lists of plant species made. Results showed that the palynological and mycological profiles yielded by the footwear and clothing of both parties closely resembled that of the wooded area, but were dissimilar to that of the park. The profile of the wooded site reflected closely its own vegetation. Faced with the evidence, the suspect confessed. The study proves the value of a multi-proxy approach to forensic investigation using exactly the same preparations.

Forensic mycology: the use of fungi in criminal investigations.

This is the first overview to be published of the whole field of forensic mycology. It is based on all available information located in the literature, together with 13 examples from recent casework. Background information on fungi is given, and this is followed by an outline of the value, and potentially wide application, of mycology in criminal investigation. Applications include roles in: providing trace evidence; estimating time since death (post-mortem interval); ascertaining time of deposition; investigating cause of death, hallucinations, or poisonings; locating buried corpses; and biological warfare. Previous work has been critically evaluated, with particular attention to its evidential value, and suitability for presentation in a court of law. The situations where mycology might assist an investigation are summarised, and issues relating to the further development of the subject are presented. A comprehensive bibliography with 120 citations is provided.

Hair as a source of forensic evidence in murder investigations.

Obtaining palynological and other botanical evidence from murder victims is becoming part of routine mortuary protocol in the United Kingdom. Forensic pathologists are often keen to cooperate in the collection of classes of material that have, in the past, been considered to be of little importance in criminal investigation. Work over the last eight years has demonstrated the great value in scrutinising cadavers for the presence of plant material and/or soil stains. Macroscopic plant remains and palynomorphs (pollen, spores and other microscopic entities) retrieved from skin and hair have allowed the differentiation of murder scenes from places of eventual deposition. Furthermore, although the opportunity has not yet presented itself, obtaining palynological evidence from the hair of suspects is feasible. During an offence, the offender might have had physical contact with foliage or the ground. Pollen and spore assemblages picked up by hair during that activity might provide forensic evidence for contact. Brief details of some aspects of case histories are presented to demonstrate the value of sampling cadavers. One case has been through the courts while the other is ongoing and, therefore, cannot be identified.

Consideration of some taphonomic variables of relevance to forensic palynological investigation in the United Kingdom.

Palynology is a long established and respected branch of environmental science that has been applied to criminal investigation in a meaningful way only in recent years. It has proved to be remarkably versatile in many kinds of criminal enquiry. It is not, however, an absolute science; palynological data are on a par with the suites of symptoms which allow medical practitioners to make diagnoses. Taphonomic variability is the main factor complicating interpretation of forensic palynological data. Palynological taphonomy may be defined as "all the factors that influence whether a palynomorph (pollen, spore, or other microscopic entity) will be found at a specific place at a specific time". If taphonomic variability is anticipated, and regularly tested, palynology will continue to keep its place in the armoury of useful forensic methods. Some assumptions made by palynologists engaged in palaeoecology and archaeology have been shown to be untenable in the forensic context. Palynological and botanical profiling of crime scenes has demonstrated anomalies which challenge received wisdoms. It has proved impossible to obtain palynological population data because every site is unique - expectations of any palynological profile can only be crude. The palynological status of any place must be tested every time. Without a body of analytical data from the actual crime scene, it is difficult to see how any palynologist can hope to present credible arguments under cross-examination. The statements made in this paper relate mainly to work carried out in the United Kingdom.

The cribriform approach to the retrieval of palynological evidence from the turbinates of murder victims.

As well as being the route for gaseous exchange, the nasal passages protect the lungs from debris and fine particulates inhaled during breathing. Foreign particles are trapped by mucus produced by membranes that line the upper respiratory tract. Even when a corpse has skeletonised, particles can be retrieved from the surface of nasal bones and may provide valuable evidence of events leading up to, and including the death of a murder victim. In this paper, we give a brief anatomical description of the parts of the nasal passages that yield most information, the methods for extraction of the evidence, and brief description of a case where such evidence has proved useful.