A few months after I started doing crime-scene work, I came across a word that fascinated me: adipocere. The sound of the word has a strange beauty that I found captivating. On learning what the word meant I was weirdly enthralled. Adipocere is also called grave wax, corpse wax or mortuary wax, though these names lack some of adipocere’s charm. The phenomenon was described by the seventeenth-century polymath Sir Thomas Browne who was one of the most innovative thinkers of his age. Hailing from Norwich, he was schooled at Winchester College before studying as an undergraduate at the University of Oxford. He then studied medicine at Padua and Montpelier universities. Browne would have witnessed anatomical dissections during his time studying and probably in his later life as a physician back in Norwich. He also had a fascination for the rituals of death. In his 1658 publication Hydriotaphia, Urne Buriall, or, a Discourse of the Sepulchral Urns lately found in Norfolk, Browne described what befalls the body in the grave; he observed that ‘Teeth, bones and hair, give the most lasting defiance to corruption’ and that on examining a buried corpse that had been buried for ten years ‘we met with a fat concretion, where the nitre of the earth, and the salt and lixivious liquor of the body, had coagulated large lumps of fat, into the consistence of the hardest castle-soap’. Browne’s description exemplifies the enquiring seventeenth-century spirit, but it also vividly describes adipocere. Incidentally, castle-soap is an anglicisation of Castile soap, a soap made of olive (Olea europaea) and laurel (Laurus nobilis) oil that originated from the Middle East.
The creation of adipocere requires very specific environmental conditions, so not all graves contain it. First, there must be a lack of oxygen in the environment. We tend to think of atmospheric oxygen as being life-giving, but in too high a concentration, it kills. Some organisms require very low levels of oxygen to survive and these anaerobes, as they are called, often play an important role in decay processes. One group of anaerobic bacteria are particularly efficient at breaking down the fatty components of our bodies into alcohol and that soapy substance, adipocere.
One of the amazing properties of adipocere is its stability. Once it has formed it can persist for centuries in the right environmental conditions. This stability is the key to its value in forensics; adipocere encapsulates and preserves the finest details, including cellular details in human tissue or in some cases the last meal eaten. In the late autumn of 1911, Patrick Higgins took his two young sons, John and William, on their last walk. He tied them together and threw them into a quarry lake near Winchburgh, Scotland. Higgins was a single parent, his wife having died in 1910, and he had been sleeping rough in a brickworks where he was working as a labourer. He had sought help in supporting the children but to no avail, and shortly before the murder, he had been imprisoned for two months for neglecting the boys. After the boys’ disappearance, Higgins claimed that they were in the care of others. Some 18 months later, the boys’ bodies floated to the lake surface and their father was arrested and charged with their murder. Despite his plea of mental incapacity, he was found guilty of murder and executed on the 3rd October 1913. Before the trial, the bodies of the boys were examined. Most of the fats in their bodies had been converted to adipocere. The adipocere preserved a great deal of their remains, including their last meal. Appallingly, the police surgeon, Sir Harvey Littlejohn, and the pathologist Sir Sydney Smith, conspired to illicitly remove some of the boys’ body parts which were then taken to the University of Edinburgh. They remained in the university until very recently when a relative, Maureen Marella, requested that the boys’ remains be cremated and a memorial service held. I have not had the opportunity to work with adipocere, but I suspect it could be fascinating. It is quite likely that it is a potential medium for preserving a wide range of trace evidence such as diatoms, pollen, fungal spores and fragments of vegetation on clothing as well as within the digestive tract. Most of this trace evidence would otherwise be lost during the processes of decay.
Like diatoms and pollen, the spores of fungi can be used to link a suspect to a crime scene or a victim. To most people, the word fungus conjures up mental images of either mushrooms and toadstools or mouldy bread. But the world of fungi is far more exciting than that. Earlier, I mentioned there are lots of species of plant on the planet − around 320,000 is the most recent estimate. This large number is dwarfed by the number of fungi, the most widely accepted estimate is 1.5 million species, although many scientists believe this to be on the low side. Not only are there a lot of them, many of them are localised and very specific about where they like to live. One of Europe’s most fascinating fungi is the nail fungus (Poronia punctata). The nail fungus is so called because the fruiting body looks rather like a small old-fashioned, flat-headed nail with little dark dots on the surface of the head. Not only is it a curious-looking fungus, it also has curious habits: it lives on horse poo. Only horse poo, nothing else will do. Nail fungus is now rare, partly because the modern antibiotic medicines we give to horses kill it. This aptitude for colonising and exploiting all sorts of unusual habitats make fungi potentially very useful for forensics. However, we have a big hurdle to leap. Compared to plants or animals, we still know very little about them. The vast majority of them are microscopic and their reproductive structures, the spores, are incredibly variable. Improving our grasp of the variability and occurrence of fungal spores could add to our environmental forensics toolkit.
There have been a few cases where fungal spores, alongside pollen, have proved significant. One such case involved a young woman who was raped by her partner. Although they had consensual sexual activity earlier in the day, the sexual contact later in the day was not, and she reported him to the police. Because of the earlier contact, it was not possible to use human DNA evidence, therefore environmental evidence was needed to corroborate the victim’s account. The suspect maintained that they had consensual sex in an open area of parkland, while his accuser said he had assaulted her in woodland. Detailed sampling of both locations and the clothing of both the victim and the suspect produced pollen and fungal spore types that corroborated the victim’s account. The fungal spores from the woodland were particularly distinctive and strongly supported the proposition that both the victim and the suspect had been in woodland. On being presented with the evidence, the suspect confessed to the crime.
12
The Case of the Scabby Ankle
Crime affects us all. It deprives some of us of loved ones and it leaves some of us poorer or with ruined homes and lives. It affects everyone’s tax bill. And it is not just humans that suffer the effects of criminality. Internationally, wildlife crime is a major concern, and in some cases is on a par with arms-smuggling, people-trafficking and the drugs trade in the harm it does to societies. The illegal and unsustainable trade in animals like pangolins, rhinoceroses, elephants and tigers is a major contributing factor towards these animals being driven to extinction. This trade is sufficiently serious that it now regularly hits the headlines. Plants are also being extirpated by illegal trafficking, yet this rarely makes the papers and campaigns to protect them don’t garner the support of royalty.
When I was a student at Kew Gardens, an illegal shipment of cacti was seized at a major UK airport. The plants were sent to Kew for identification and care prior to the court case being held; this is another example of the services that botanical gardens provide to society. Many cacti are increasingly at risk of extinction owing to their popularity in horticulture. People who illegally harvest wild cacti are rather romantically described as cactus rustlers, though there is nothing romantic in their actions. They are robbing the Americas (where all but one of the world’s cacti species originate from) of its biological treasures. One of the seized cacti sent to Kew had been ripped out of the ground by a truck, using a rope tied around the cactus. The cactus had half-moon shaped cuts in its stem where the rope had dug into it. Luckily, the plant survived and was ultimately incorporated into Kew’s Living Collections. Every time I return to Kew, I pop into the Princes
s of Wales Conservatory to wish it well. It’s quite close to the path, so see if you can spot it – the damage is still visible.
Forensic science is increasingly being deployed to combat this trade and other illegal activities directed towards wildlife. Orchids are particularly vulnerable to our depredation. Like cacti, many orchids are widely traded legally, but there is also an extensive illegal trade in live plants stolen from the wild for the lucrative and very large international black market. They are also often found in various traditional medicines and foods. As populations rise and demand increases, formerly sustainable, traditional harvesting has turned into widespread exploitation. The problem is sufficiently severe that many countries have specially trained police specialists fighting wildlife crime. In the United Kingdom, the National Wildlife Crime Unit was set up to combat cruel and criminal acts such as the persecution of birds of prey (raptors), hare coursing, badger baiting and fox hunting. People illegally collecting and trading in stuffed wild birds (especially raptors), bird eggs, butterflies and wild orchids are also significant targets for investigators. Much of this work is undertaken using various surveillance techniques, as well as newer approaches involving non-human DNA and hair- and feather -follicle identification (the hairs and feathers of many animal species can be identified using microscopy and comparison with museum collections).
Forensic laboratories investigating wildlife crime increasingly use DNA-based tools to identify processed or powdered materials derived from some of the planet’s rarest and most endangered organisms such as rhinoceros horns or dried orchids. Several years ago, I visited Yunnan in southern China to film a documentary for Discovery Channel on China’s amazingly diverse plant life and how the people of China are still, despite globalisation and modernisation, dependent upon this bounty. One of the segments we filmed was about the developing horticultural industry growing orchid species for traditional Chinese medicine (TCM). One of the most important plants in TCM and one of the nine ‘magical herbs’ is an orchid, Dendrobium officinale, which is known as Tie Pi Shi Hu (铁皮石斛, iron skin dendrobium) to the Chinese. This plant has been harvested from the wild for hundreds of years and is now sadly at risk of extinction as a wild plant. The Chinese are trying to meet the burgeoning domestic and international demand for this plant by cultivating it, but wild -collected plants are still sold for a premium. One of the ways that trade can be regulated is through laboratory testing. These laboratories depend upon museum and botanic garden collections to provide valuable resources for comparison and to validate identifications of seized goods.
Not only do biological collections hold valuable material for fighting wildlife crime, they are repositories of information that can help us understand the emergence of new diseases. In 2009, some of the first cases of what became known as seasonal canine illness were identified on the Queen’s estate at Sandringham and at other locations across the country. The illness caused some dogs that had been walked in woodland to start vomiting and to have diarrhoea. In severe cases and without veterinary intervention, the dogs died. Not surprisingly, the unexpected and rapid arrival of this illness across the country caused widespread concern among dog owners.
Researchers at the Animal Heath Trust led the efforts to discover what was the source of this mysterious and distressing illness. A wide range of causes were suggested, including agricultural chemicals, rodenticides or illegally placed chemicals used to kill birds of prey. There were also suggestions that the cause might be botanical. One popular suggested cause was blue-green algae. These are fascinating organisms that are more closely related to bacteria than to other types of algae or land plants. They are found in an incredibly wide range of environments around the planet and are ecologically very important. Some blue-green algae, or Cyanobacteria as they are collectively known to scientists, commonly form part of the symbiotic union with fungi that we call lichen. The beautiful hues of orange, brown, green and grey lichen that adorn our trees, rocks and buildings would not exist without them. Some blue-green algae also have a reputation for causing poisonings of either humans or animals. These poisonings normally occur after contact and ingestion of inland waters polluted by agricultural fertiliser or animal-waste run-off. The excess nutrients cause algal blooms, meaning that some blue-green algae populations proliferate and thrive, sometimes to environmentally hazardous levels, in the nutrient-laden water.
By 2011, the number of seasonal canine illness cases had gradually increased, and concern grew. Early that September, I joined Animal Health Trust researchers at the Sandringham estate to investigate the possibility that there was a botanical cause. We met a couple who, just a few days earlier, had gone for a walk in the woods with their dogs. Shortly afterwards one of the dogs rapidly became ill and died. I spent the day dashing in and out of the bushes looking for clues, but I was unable to see anything that could have caused the dogs to sicken and die. I looked for likely sources of toxic blue-green algae but found none. I also scouted for toxic fungi and plants. While the wood did have some of these, such as foxglove (Digitalis purpurea) and cherry laurel (Prunus laurocerasus), all the plants and fungi I saw had been present for many decades. If they had been the cause, the illness would have been noticed decades earlier. We had drawn a blank. I must admit, from what the Animal Health Trust researchers had told me beforehand, I was not expecting to find a botanical cause. I suspected a virus or an insect.
On my way back to London, I felt a little itch around my ankles, and by the time I got to bed it was becoming bothersome. When I woke up the next morning my ankles had ballooned and were bright red. I headed straight to the doctor and described what had happened. We both suspected that it might have been caused by some unseen critter. My doctor prescribed some anti-histamines, and by the end of the day the swelling had gone down significantly, but my ankles still looked awful. I took a photograph of them and consulted one of my colleagues at the Natural History Museum who is an acarologist, an expert on mites.
Mites belong to the same evolutionary group as spiders. Many of them are plant pests but some cause illnesses in animals. These mites are known either as harvest mites or chiggers and are largely confined to the warmer parts of the world. Worldwide, some harvest-mite species transmit some rather nasty disease-causing organism, such as the bacteria that is the cause of scrub typhus. My colleague agreed that my symptoms were consistent with harvest mites. It seemed likely that I had picked up my unwanted guests while I was rummaging in the undergrowth. However, none of the species found in Great Britain were known to cause such symptoms. Is it possible that there is a new harvest-mite species or a disease-causing organism that is vectored by them here in the UK? This is a plausible explanation; biologists have documented large-scale migrations of plants and animals due to environmental change over the last few decades. We also know that international trade via shipping and aircraft is an important ‘pathway’ (as it’s described in policy-speak) for biological invasions. To date, we remain unsure, but harvest mites have been observed on dogs suffering from seasonal canine illness and they appear to be the strongest contender as the causal agent.
The following autumn, the museum was contacted by a producer from the BBCs Countryfile television programme. Would I do an interview alongside the Animal Health Trust describing our investigations? I agreed and a few days later I met Countryfile presenter Tom Heap at Sandringham to do the interview. I was prepared and relaxed; one of the skills that my time at the museum taught me was media work. My first contact with Countryfile had been with one of my childhood heroes, John Craven. He interviewed me about a research and citizen science project on bluebells that I had been working on. We met in a wood in south London. Unfortunately, it hammered down with rain all day and we both had awful colds. I remember sitting in the car with him, glumly wishing the day would just end and I’m sure he felt the same way too. Nevertheless, I was a little star-struck. Luckily, the weather on the day of the interview with Tom was much better and all went well. We spent several hour
s retracing our earlier step through the Sandringham estate (this time I avoided clambering through the undergrowth) while being filmed by the BBC crew. Foolishly, I mentioned the picture of my mite-ravaged ankles. The team were very keen to have a copy for the programme and several weeks later, my scabby ankles appeared on the programme I’m quietly optimistic that one day they may prove to have saved the life of someone’s dog.
As well as hunting for poisonous plants and fungi in our landscape, I have also grown quite a few. In my teens, I had a flowerbed devoted to poisonous plants: monk’s-hood (Aconitum napellus), hemlock waterdropwort (Oenanthe crocata) and oleander (Nerium oleander) were favourites. My mum and I used to happily muse on the lethal dose required to despatch my father, who had long since removed himself from our lives. It’s fair to say that my family can be quite dark sometimes.
I have worked on one or two cases involving poisonous plants and fatalities but, for me, they are rare. This rarity is probably due to several reasons. First, many potential poisoners would have no idea what plants were poisonous and how to find or identify them. So, in most cases, poisoners (or people attempting to commit suicide) tend to reach for the medicine cabinet or the chemicals in the garage or the garden shed. Secondly, most unrefined plant toxins are relatively inefficient and slow working compared to what can be found in a bottle on a shelf. It can take quite a long time to die from some of the toxins present in plants or fungi found in the UK, and there is always a risk that the victim will vomit them up. Finally, there is quite a high chance that the victim will recover from poisoning by most plant toxins if they are treated in time.
Murder Most Florid Page 14
