Traces

by Patricia Wiltshire

  One thing that needs mentioning was that one of the first tasks in this whole case was to analyse the swabs taken from the genitalia of the two litigants. No particulates were retrieved from the male, but the swabs of the girl’s vagina yielded two grains of oak pollen and one of grass. It is obvious to anyone with an imagination that the boy’s hands might have transferred the pollen to his penis then secondarily transferred it to the girl. Or, of course, his penis might have touched the ground, and then there could have been a direct introduction. The tree under which the attack had taken place was an oak, and how could that oak and grass pollen have reached the intimacy of the girl’s body unless it had been put there?

  Once the young man’s barrister had had time to digest our evidence, the boy quickly confessed. This saved the country a lot of money as court cases cost a fortune. I am glad to say that a fairly large number of our cases have resulted in confessions so we have saved the taxpayer quite a lot. But although it is always important to be careful of confessions in case they were obtained under coercion or other illegal means, this putative rape was certainly recorded as an actual one, and the young man was given a custodial sentence commensurate with the harm he had done.

  7.

  A SPIDER’S WEB

  Pollen and spores are robust and, where bacteria and fungi are kept at bay, they can endure for thousands of years, even millions of years in some rocks. In archaeology and ecology, this makes them of great value for reconstructing past environments and demonstrating landscape change. Plants are also pivotal in human history, and their remains are testament to the ways they have been exploited over millennia.

  On one occasion I was briefly baffled by a case brought to me by the police from a mining town in Yorkshire. Two boys had found a heavy, new sports bag lying in the road. It was so heavy that it must contain a lot of equipment, and they carried it home, full of excitement. They could not wait to see what was inside, but the fright they received served them right; what was revealed by the unzipping would have unnerved the toughest of men. A mummified corpse, as alarming as anything they had seen in horror films, was inside, and the boys’ screams and yells brought their parents running, and soon telephoning the police. No one had a clue about the identity of this dead man.

  Except for the lower legs and feet, which were inside a loosely wrapped plastic bin liner, the whole body was tightly encased in cling-film plastic. A solitary yellow sycamore leaf was stuck to the thigh and, from the shins down, the skin was covered by a black, sooty material. The two officers who brought me the sample said that the corpse stank and the smell was very likely that of the black stuff. They agreed with me that it was a chemical smell and probably some kind of engine oil. I quickly made a temporary slide preparation of the ‘soot’, and the view under the microscope left nothing to doubt; it was a thick mass of fungal spores. This presented us with quite a puzzle. I realised that the looseness of the wrappings around the lower legs and feet meant that they were exposed to the air whereas the cling film prevented oxygen reaching the rest of the body. Nearly all fungi (though as recently found, not quite all) are like us in that they need oxygen to live and grow. This meant that while the rest of the body was the brown of mummification, the feet were as black as soot, and this soot consisted of the spores of an actively growing fungus.

  Everyone was interested in the leaf and, after some effort, I was able to obtain quite a few pollen grains from its surface. Again, the ‘picture of place’ was an unkempt garden and, strangely, there was plenty of rose-type pollen, some Clematis, and some pollen of sycamore, pine, and birch. These were all hints of the place the leaf had come from. A post-mortem had established that the man had been stabbed, but it was impossible to determine how long he had been dead. What was curious, though, was the sand that was stuck to the skin on the back and front of the torso and in his hair. The young police officers were flummoxed, although it was obvious that they were enjoying the variety offered by this case, their first encounter with a murder.

  As it turned out, the victim was identified by a sheer fluke; the facial reconstruction eventually came through and ‘wanted person’ posters of the face were distributed all over this part of Yorkshire. Bizarrely, it was one of the police vehicle mechanics, working in the depot attached to the police station, who recognised the face as belonging to a Yemeni immigrant who lived not far from the police station. The extraordinary twist in the story was that the victim had worked in the same depot before he had gone missing. His home and family were quickly identified and it was of interest to the police that his house had been put up for sale.

  When I got to the terraced, red-brick, Victorian house, I was struck by the mutilated remains of what had been a huge rose bush immediately outside the back door, which opened onto a tiny, concrete backyard. The remains of an old Clematis plant still straggled on the fence next to the rose. The rest of the garden had been stripped and was weirdly empty; somehow, the topsoil had all been removed. But there was a sycamore tree at the end, overhanging the garage and the next door garden.

  The pollen profile suggested that when the killers had wrapped the body in plastic cling film, they had laid it on the backyard, next to the rose bush and Clematis. There was a great deal of organic, decomposing plant litter on the concrete and this had probably collected rose and Clematis pollen; this could have happened when the bush was chopped down and residual pollen was recirculated.

  The yellowness of the sycamore leaf yielded information too. In fact, from that single leaf, I was able to build up a picture of the main features of the part of the garden near the house, and the possible circumstances around the man’s death. If it had been pulled from the tree when green, I would have expected it to keep its greenness since chlorophyll does not readily break down when leaves are detached prematurely from the parent plant. But, an autumn leaf that has already yellowed would have floated from the tree naturally, and could have blown up onto the backyard from the bottom of the garden. This gave a hint that the corpse had probably been wrapped up in the latter part of the year rather than in spring or summer. But sycamore leaves decompose quite quickly and might have contributed to the organic mush on the concrete if we were looking at late autumn or early winter. What had been picked up by the body had been an early autumnal leaf, and it had been protected from breakdown by the very circumstance that prevented fungi growing on the body other than the feet; a lack of oxygen, because of the tight plastic overcoat encasing the corpse, had prevented decomposition of that important piece of evidence. Indeed, that single leaf had preserved the picture of the garden to tell us part of the story, but there was plenty of other evidence to implicate the victim’s son and grandson in the crime.

  The cellar of the house revealed a burial place, as well as the source of the sand particles that had been stuck to the victim’s skin. At the bottom of the cellar steps, officers found a brick-built cell, freshly painted in green gloss paint and filled full of sand. Analysis showed that it was builders’ sand, and that it was heavily contaminated with diesel oil. We were astounded to learn that during the Gulf War, the Yemenis routinely doused the dead with engine oil and then buried them in the sand. This was certainly not a Yorkshire tradition, and long police interviews with the perpetrators revealed that the son and grandson had copied what they had witnessed in the Gulf War. The grandfather had been a domineering and cruel old man. They just could not tolerate him anymore and, in an outburst of anger, resorted to drastic action when, as punishment for some trivial misdemeanour, the old man had put his kukri knife in the fire and deliberately burned his grandson’s leg with the blade. They had grabbed the knife from him and stabbed him with it.

  Early in the investigation, I was asked to find out as much as I could about the house, the people, and their habits. There was a coal shaft leading straight from a trapdoor on the outside pavement into the coal cellar, and it was impossible for me to resist taking a sample of the coal dust from the shaft. The contents of that sample were difficult to
interpret, so much so that I got a headache, which only lifted when I realised what I had found: a rich profile representing a hay meadow, with pollen that was so well preserved that it looked as though it had been shed that day. But then a moment of epiphany: I remembered that, when I was young, people still used horses and carts. These would once have plied these terraced streets daily and, when the coalman stopped to shovel coal into the cellar, his horse would have had a break too. From my childhood in Wales, I well remember dollops of steaming manure, at intervals along the street, dropped by the various tradesmen’s horses. It was precious stuff and keen gardeners used to rush out to shovel it into buckets. Of course that was the source of the hay meadow in the cellar.

  Horse dung is very friable when it dries, and it blows around, into gutters, and any nook and cranny. Generations of dung debris, with its pollen load, had found its way into the coal shaft, and the sulphurous coal dust had been so acidic that all microbial activity was prevented such that the pollen was beautifully preserved. It had survived the extreme chemistry of the horse gut and had lain in that shaft probably since Victorian times, but certainly since at least the 1940s or even early 1950s.

  Such a discovery has helped me better understand weird pollen profiles ever since. I have learned to envisage a site as it had been, or is being, used and I have since found hay meadow pollen deep in woodland, away from any farmed fields – again the result of dry horse manure blowing in from bridle paths. It is no surprise, then, that prehistoric pollen has been extracted from the dung of woolly mammoth, last known to roam Earth some 10,000 years ago, and from the gut of the Iceman found in 1991, a Neolithic hunter who roamed the Alps over 5,000 years ago, the arrow that killed him still embedded in his shoulder blade. Often, these pollen and spores from guts are very well preserved indeed.

  With pollen grains surviving for millennia like this, it is perhaps no surprise that the clothes of the alleged victim and perpetrator in the North Wessex rape case had proved so important. But even when a person has been sufficiently forensically aware to destroy their clothes, or swap them with someone else’s, trace evidence is not necessarily lost. Alive or dead, most of us, my dear husband excepted, have a natural attribute that can trap palynomorphs. Our hair follows us wherever we go and, whether we use hairspray, gel or other products, pollen and spores will stick to it tenaciously by electrostatic forces, and this leads me to another case entirely.

  The girl had been missing for almost a year when, in the dying days of summer 2001, she was discovered in an excavated depression on the borders of a Yorkshire forestry plantation. She was still wrapped in the duvet which her killer had hastily put around her body. Not yet 15 years old when she had vanished, her disappearance on the way home after a shopping trip with friends had sparked one of the largest missing person’s operations in the history of Yorkshire policing. Two hundred officers and hundreds of volunteers had fanned out through the streets and along the bus route she took home, knocking on thousands of doors, searching 800 houses, sheds, garages, and outbuildings. Search warrants were issued, 140 men with past convictions investigated, collections of household waste curtailed while refuse sites were searched – and a local benefactor even offered a £10,000 reward for information leading to her return. But none of it mattered: she would never return home.

  It was a dog walker who found her, as it so often is. Her grave lay only 100 metres away from the spot where another murdered girl had been discovered some ten years before. Inside a floral, polycotton duvet cover, her body was swaddled in several green plastic bin liners; a black bin liner was over her head, secured by a dog collar around her neck. At the burial site, a mixture of native hardwood species had been planted along the adjacent road. This is commonly done by the Forestry Commission to give the impression that their alien plantations are more diverse than they really are. Emerging from the woodland edge and towards the road, there was an open area consisting of acid grassland, with occasional patches of heather, bilberry, and bracken fern. This kind of terrain is common in Yorkshire and other parts of the UK where the Forestry Commission, and private land owners, spread these dark, brooding woodlands all over our hillsides. They are shady and unkempt inside, and the trees are invariably regimented into straight lines; they are deeply forbidding to our native wildlife. I always view them as blankets of doom and gloom, and can hardly bring myself to grace them with the title ‘woodland’.

  When I arrived at the burial site, some police officers and a couple of suited-and-booted scientists were busying themselves, but the scene was quiet and hushed. I was not very pleased to see the forensic archaeologist already into deep excavation, having paid no attention to preserving the area immediately around the grave. This meant that critically important places for me to obtain my surface samples would have been destroyed by being contaminated by the grave-fill. I busied myself taking uncontaminated surface samples as close to the grave as I could, and surveying the vegetation around and in the vicinity of the grave, and along the offender’s putative approach path. I made a comprehensive species list so that, if it were necessary, I could compare this woodland’s botanical profile with any that I obtained from the offender’s belongings, assuming that the police would manage to arrest one.

  There was a small silver lining among this grim, desolate scene: the way this poor little girl had been wrapped up meant that she had not been exposed to the grave soil or surrounding vegetation. Whatever trace evidence I might retrieve from her would not represent the woodland of her burial but would represent the last place she had made contact with the ‘outside world’. That might lead us directly to her killer.

  It was with this in mind that I arrived at Leeds General Infirmary a month after the girl was brought up out of the woodland. Her body had been made ready on the stainless steel mortuary table and my first job was to wash as much trace evidence as I could from her detached scalp.

  Hair, and the same goes for fur and feathers, is amazing stuff. It is made of the highly resistant protein keratin, which also makes up nails, hooves, and claws. It is strong and durable. The only other biological matter that comes close to it for toughness is chitin, the principle component of the shells of crabs, the outside skeletons of insects, and the walls of fungal cells. Natural fibre does not get much tougher than hair, and its durability is a great boon for those of us looking for particulates stuck to its surface. I have found that if hair contacts a surface covered with particles such as pollen, any kind of spore, and even minerals, they will quickly be transferred to any strands coming in contact.

  Each hair is made up of layers: first, an innermost medulla, which is present in only the thickest types of hair; then a cortex and, finally, an outer cuticle, consisting of overlapping scales which gradually erode as the hair grows old. Because hair exhibits various static electric forces, it actively attracts particulates – and this means that it can, under the right circumstances, act like a spider’s web, trapping palynomorphs that we can later recover. Pollen and spores can be held on hair and fur for incredibly long periods. In archaeology, they might be recovered millennia later and used to help us reconstitute an idea of the prehistoric landscape. In a forensic context, pollen and spores might be retained on hair indefinitely. Before, during, and after death, hair will draw palynomorphs to it so that I can retrieve the evidence from it. From a victim’s hair, I have often been able to envisage the kind of place where the body has lain, even when it has been in more than one.

  Sometimes, the hair of a murder victim is clean and well groomed, but not always. I often have to work on hair matted with blood, other body fluids, and the slime of decomposition; it may be coated with dirt, soil, and other materials. Even a week or so after death, the scalp can become detached from the skull and, with the skin tissue putrefying faster than hair decays, it is not unusual for a victim’s hair to be found some distance from the corpse itself. Indeed, at crime scenes where corpses are exposed on the surface rather than buried, hair can become spread out across the
surrounding ground. I have seen birds gathering it; it is, after all, excellent nesting material.

  One of the reasons for the month-long delay in my part of the investigation was that the state of preservation of the victim was so good it was thought impossible for her to have been buried for the whole eight-month period of her disappearance. The pathologist felt she might have been kept in a freezer, or somewhere else very cold, and then buried at the offender’s convenience. This meant that she could have been in her grave for a relatively short period. Of course, one had no idea of the length of the freezing period even if, indeed, she had been frozen. The police employed experts from the frozen food industry, and the state of muscle in frozen meat was investigated. However, as in so much of forensic work, observations and experiments are not strictly scientific because one can never replicate the original conditions to test one’s model or hypothesis. Everything must be approximate, but it is the best that can be done under current legislation, and it is certainly worth attempting more creative ways of testing one’s ideas.

  ‘What we need, Pat,’ the detectives had said to me, ‘is some idea of the place she’s been kept all this time …’