Traces

by Patricia Wiltshire

  Still with my eyes tightly shut so that nothing would distract me, I continued: ‘Looking at the results from the car, it seems as though it was driven up a forestry trackway, which had a dry, sandy soil, but might have had damp ditches at the edges, or in ruts. I can see that it is fairly open, but there is a lot of woodland with commercial conifers and a mixture of deciduous trees, mostly oak, beech, hazel, but with some sycamore and elm. There are damper soils because we have willow and alder. There also seems to be a lot of ivy and bramble.’

  My picture was tentative but, during fieldwork, and under the microscope, I had seen these plant communities many, many times before; and my results screamed ‘Forestry Commission’. But although I could easily recognise the plant communities, one thing I had learned very early in my career was that no two places have identical vegetation. Each is unique in the patterning and density of various plant species and, although I could describe the kind of place that Dyson had visited, I needed something special and unusual if we were to find the location.

  I could tell a lot more from the rather cursory results but pinpointing the location would take a great deal of extra work. Within limits, I can fairly easily describe a picture of a place from the pollen evidence, but to find the location of the image is not quite as easy, especially if I am not familiar with the particular part of the country in the frame. I can predict the soil type and, often, the underlying geology, but in this kind of case, it is generally more efficient to ask someone who knows the local botany to use my description and do the groundwork.

  I continued, ‘Ray, you will need to go along an open track and eventually, probably quite near the path, there will be a stand of mature birch trees. That’s where you’ll find her. Oh and…’ I stopped, because I was certain the next words I was about to say would seem the most unbelievable of all, and yet, I was certain they were true.

  ‘She won’t be buried under the ground at all.’

  There was a silence, and I could now sense a measure of disbelief, but he just listened while I carried on: ‘She’s in a hollow, off the path, and will be covered over with birch twig litter.’

  I let that last thought of Joanne’s resting place linger, because this was the image I had seen most vividly.

  ‘How certain are you?’ Ray asked.

  It is a question you must always ask yourself, so you must also forgive it of others, at least if they ask politely without an accusing disbelieving challenge I so often encountered in the early years.

  ‘Pretty certain, Ray.’

  There was a time when I was astounded myself at the specificity of the evidence I could produce, the detail that I could spirit up out of the images at the end of my microscope’s lens. But no more. Witnesses fabricate and misremember details so that two accounts of the same moment are only exceptionally exactly the same; video and still photography capture only part of the story, leaving out the wider context and subliminally directing your thoughts; but pollen profiles can be interpreted by competent palynologists who, in addition, have extensive field experience. There are always surprises, though, not covered by the textbooks and, again, this is where experience is golden.

  From all the samples I had prepared, it was clear that Joanne’s boyfriend had visited a wood which had, in addition to spruce, other commercially important conifers, including pine and some western hemlock. There were also deciduous trees, with birch being utterly dominant in the profile. It was an interesting assemblage of trees and other plants, and their distribution between the various exhibits was revealing. The place obviously had an acid, dry soil, but there were damper areas, too. It seemed to me that the vehicle’s spoiler would give me a wider picture of the place because, as the car had been driven to the final deposition site, it would have picked up evidence all the way from the entrance of the woodland to where Joanne lay. Most likely, Dyson’s feet would only have picked up evidence from the actual place where he had put the body, and this would also have been carried on his shoes to the inside of the car.

  Birch dominated the profile, but pine was reasonably abundant. Oak, hazel, beech, heather, ferns and grasses, typical of woodland and woodland edges, added to the jigsaw of an image. I was looking at residual pollen and spores; they had been produced in the previous growing season, or even before that. Hazel flowers from about December, but the others in the profile would have been produced from the later spring onwards in the previous year. In other words, the evidence had been hanging around on the surface of the ground, in soil and on vegetation, since the previous season, probably even further back than that. No matter what the time of year, there is nearly always something for me to analyse and build up a picture of a place, even if that place looks unpromising to the police.

  I continued to search the slides.

  I retrieved nothing at all from Dyson’s jeans, and mostly grass pollen from his Nike trainers. Obviously, he had probably not worn these when the offence was committed. But when I looked at the slides from the Reebok trainers, the foot pedals, and the car spoiler, the place leapt out at me. It was already clear to me that we were dealing with a woodland dominated by commercially grown conifers, but now, as more slides were scrutinised, other pollen types started to be revealed. The mixture of palynomorphs made perfect sense. Plantation owners often include native deciduous trees, including birch, at the edges of their plantations to mask the dense, boring monoculture of conifers. Birch cannot stand the shade, it grows well in poor soils, and its life expectancy is about the same length of time that it takes conifers to reach a size suitable for cropping. One can see why this ‘weed’ tree is a certainly favourite of plantation owners.

  The richness of the material retrieved from the spoiler of the car suggested to me that Dyson had driven the car deep into the site, looking for a likely place to bury Joanne. The insides of the car revealed a miniature mystery nestled inside the bigger one. Even though Dyson’s Reebok trainers had been thick with pollen from the woodland itself, none of this seemed to have transferred to the driver’s floor mat – which was unusually clean, betraying only a couple of grains of pine pollen and a single grain of heather. Was Dyson sufficiently aware of forensic science that he had brushed, vacuum cleaned, or even scrubbed the floor mat? It certainly seemed so. Yet the mat on the passenger side revealed the same rich assemblage as his Reebok trainers had, and images of how this came about flashed into my mind. To lift something big out of a car, you sometimes have to step into one of the footwells to brace yourself. I could imagine Dyson, readying himself to lift Joanne out of the car and, grappling with the weight of her body, planting his foot down on the passenger footwell mat to get better leverage.

  I had established that we were looking for a forestry plantation but I needed something to pin point its location and the kind of place within the woodland where Joanne might have been placed.

  Realisation came by virtue of the garden fork.

  There was a lot of birch pollen on Dyson’s footwear and where he had transferred it to the passenger-side mat of his car. But, when I examined the sample from the garden fork, I was staggered. There was birch pollen up its shaft, birch pollen on its handle, but, on the tines, it was thick to the exclusion of almost everything else except a few grains of pollen from typical garden plants.

  An image of a place suddenly forms in my head. It is not as magical as it might seem. It is a intuition built upon all my years of slogging through basic subjects, trekking, and working in the field, and continuously accumulating reams of knowledge about the natural world around us. All this is stored and processed in a remarkable super-computer, the human brain.

  This time I saw it clearly: how Dyson had driven Joanne’s Vauxhall Estate along a Forestry Commission track of dry, sandy soil; how the commercial conifers had risen up starkly around him until he found a place where the trees were not so dense. And eventually, he came to a stand of birch. This seemed the perfect place. Digging a grave is hard work, and digging a grave with a garden fork is impossible. A fork
is no good for digging a grave but it certainly is good for scraping.

  If you spend any time wandering through woodland and plantations which are often at the edges of heathlands and moorlands, you notice the dense build-up of twiggy litter. It collects in hollows, and one can get caught out by thinking there is solid surface until you stumble into a hole. The floors of plantations are riddled with undulations, where clumsy furrows, made by forestry workers, create hollows and hammocks, and are mementoes of past planting and felling. Why bury a body when you could find a suitable hallow and just scrape litter over it to mask its presence?

  I suspected that he had carried Joanne’s limp body, placed her in a convenient hollow not more than 100m or so from the track. Behavioural profiles have worked out that about 100m is the limit of someone being willing and able to lug the dead weight of a corpse. I imagined him stumbling, his Reebok trainers sinking into twiggy litter, he would have panicked, realising that it was too difficult to bury her. But he could hide her. I thought he could have rolled her into one of those hollows and, using the garden fork, scraped the birch twig litter over her, masking her from view. Of course, she had to be in a hollow so that sufficient litter could cover her. If she had been left on a flat area, there would have been a body-shaped mound of litter, and this would have been very obvious.

  He must have thought it would be a very long time before she was found. In that bitter winter, close to St Valentine’s Day, not much forestry work would have been going on. It was very cold for bluebottles to be searching for sites to lay their eggs, and the smell of death would be delayed. This meant that foxes and badgers may not have found her as readily as they do bodies buried in high summer. She might have remained undiscovered for ages – perhaps forever.

  As he was scraping the twigs over her with the fork, he was blissfully unaware that he was also coating the fork’s tines with the birch pollen that would later help bring Joanne Nelson home, and lead him to court.

  ‘But where is this place, Pat?’ Not close to Hull, that is for sure. It has to be a plantation that included western hemlock, all the plants in the assemblage, and a specific fern that, at first, did not ring too many bells for me because it is so common over so much of the country. This is Polypodium, the polypody fern. It is incredibly common in the south and west, and even in Surrey where I live, but in this part of Yorkshire it is decidedly uncommon – bordering on rare. What a piece of luck. The distribution of this fern could be checked in the maps of the Botanical Society of Britain and Ireland, something I do on a regular basis. What was so interesting was that the polypody fern had been present in the area in the past, but was now absent from the area altogether. The historical records showed where it had grown before, and this enabled huge areas of terrain to be eliminated. There were three possible woodlands that had western hemlock but only two of these had had polypody fern in the past.

  Dyson had already said that he remembered a metal gate with lots of empty bottles lying to one side of the entrance. The sergeant in the case was brimming over with enthusiasm and could not help calling in various experts, sometimes inappropriately and irritatingly. However, a local botanist in Hull looked up the record maps and found the historical distribution of polypody fern before I had a chance to suggest it myself, but that did not matter. We just had to find this young woman for her parents’ sake. Not for Joanne’s. She had gone, but her grieving and fearful family were desperate, and Ray Higgins was determined to bring her back to them.

  The police were besides themselves with the new information, and they set off with Joanne’s murderer cuffed in the back of a police car to scour the winding roads of that landscape, looking for a metal gate and bottles on the edges of the woodlands that had been pinpointed. They were just too keyed-up to wait, and they drove along miles of roads until, weary and dispirited, their eureka moment came: here was a pale, metal gate, and the bottles were still there. I would love to know how they felt but I expect it was excitement mixed with relief.

  They found Joanne’s body quite quickly, and later said they were taken aback at the accuracy of my description. They found Joanne down a slope, just off the track in a hollow, beneath birch trees and covered with birch twigs. So, years of slogging at basic subjects, trekking, and working in the field, putting several and several together, binding it with common sense, and having the courage to speak the vision, paid off.

  I was not there on the day they actually found Joanne Nelson’s body and finally confirmed for her anguished family what they must have known all along, but I have often imagined how it must have felt to be one of those police officers who were initially sceptical of my vision. Long after Dyson had been convicted, Ray took me to where Joanne had lain. I had been taken aback at the accuracy of my description of a hedgerow and field in my very first case, which I will come back to later, but I was just as shocked as I walked with Ray through that fateful gate. Here was the sandy path used by forestry vehicles. It was deeply rutted and sparse heather sprouted both on the top of the ruts and along the tops of the gouged edges. Common heather tolerates damp conditions but does not like standing water; the hollows were certainly damp, however, and a shallow, stagnant ditch rang along the path edge for some distance. There was an open area to the left dominated by bracken ferns and, as far as the eye could see, dense trees stretched from the right side of the path and straight ahead. The tree plantings reflected what I had found on the microscope slides: there was a lot of pine, western hemlock, and spruce.

  There is one facet of the Joanne Nelson case that always helps me explain the way a forensic ecologist can work. I had come to know the type of landscape we were searching in. I knew its trees, and so the nature of the soil, and the non-tree plants on the ground that could be expected to be growing with them. I felt as if, in my mind’s eye, I could follow Paul Dyson down the track to where he had hidden the body. But Yorkshire covers a huge area and there could be many places that might have fitted the template I had built up. After all, there are plantation forests with stands of birch trees across the county. The police could perhaps have scoured them one by one, if they had the resources to do so – but nature had given us one final clue to point the way. For there, in the microscopic remains retrieved, was the pollen of western hemlock and the spores of polypody fern.

  Even after all these years, I never fail to be impressed how pollen profiles can give so much information, thoughts, conjecture and visions, all based on scraps of evidence that, although tangible to me, must have seemed like superstition or magic to others.

  In recent years, some geologists have been trying to help in cases like these. One in particular, 20 years ago, worked on cases, convincing police officers that trace evidence provided by mineral particles in the soil was infallible. He became known by the size of his invoices, which were invariably inversely proportionate to the amount of information he could provide. He cost various police forces a great deal until he was eventually discredited and, even with his protocol of taking literally thousands of samples, he could not get the resolution that plants can provide from a few simple samples, a microscope, and a dash of medicated shampoo used to wash the exhibits. In one case he came up with the same location as me, but at the cost of analysing over 1,000 samples collected along a transect line over 50 miles in length, whereas I reached the same result with just four samples from a spade, and doing some observational field work. If you know the ecology of your plants, you can predict the kind of soils they will be growing in and, therefore, the geology underneath them.

  There is too much superstition around. But I do not do magic. This is science. Twenty years earlier, Joanne’s body might never have been discovered until her scattered bones were stumbled upon by a forestry worker, or chanced upon by a solitary dog walker. But with the science I have pioneered, we were able to detect the place her murderer had visited by the microscopic traces left behind by nature. Whether we are murderers or not, we leave our paths behind us – and a person who understands landscape,
pollen, other palynomorphs, fungi, and soils can follow them.

  I received a letter from Joanne’s parents thanking me for bringing their girl home. I must say that, until then, I had thought of Joanne as more of a puzzle and was too engaged in finding information to think about her as a person. In a world where you are faced with some of the worst things that human beings can do to one another on a daily basis, it is all too easy to become desensitised, to lose yourself in the intellectual challenge and park the human cost. Sitting in my study with my beloved cat upon my lap, reading Joanne’s mother’s words, something changed in my perception. Joanne Nelson was not only a puzzle that needed to be unpicked. She was not only a challenge for me to confront with the years of experience I had acquired. She really had been a living person, with loves, hopes, fears, and ambitions. With the words of her mother came that realisation, and with it a rush of emotion that I rarely feel. And this, more than the intellectual challenge, more than the pride I have always taken in advancing the science of forensic ecology, is why I do what I do. People’s feelings matter.

  3.

  PROXIES OF THE PAST

  It is time, perhaps, to go back to the beginning.

  I did not mean to become what I have become and this, of course, is how all the best stories start. I was already in my early fifties when I got the telephone call that would change the course of my life, drawing me into the world of forensic investigation. By then, my career was already what you might call wide and varied. I had started my working life training as a medical laboratory technician at Charing Cross Hospital, and was involved in the second renal dialysis unit in Britain. I was certainly used to dealing with blood and excrement and having to put up with vile odours; it was part of the job. Eventually, I became involved in research projects, and this meant dealing with laboratory animals. I came to love the rats – white, pink-nosed, twitching little things. They were curious and loved being cuddled and tickled. I loved the animals and hated the research programme, and I decided emphatically that medical research was not going to be my career.