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Maggots, Murder, and Men
Memories and Reflections of a Forensic Entomologist
By Zakaria Erzinçlioglu St. Martin's Press
Copyright © 2000 Y. Z. Erzinçlioglu
All rights reserved.
ISBN: 978-1-4668-5242-6
CHAPTER 1
A very simple clue
'Who saw him die?'
'I', said the Fly
'With my little eye,
I saw him die.'
Anon., 'Who killed Cock Robin?'
Viewed dispassionately, a dead human body is a magnificent and highly nutritious resource. Such a resource, suddenly made available in Nature, will be rapidly colonized by various insects as well as other invertebrate animals. As time passes and decomposition progresses, different insect species will be attracted to the body at different stages of decay. Bluebottles and greenbottles will arrive to lay their eggs which hatch into maggots that feed voraciously on the tissues. Beetles will arrive, not only to feed upon the tissues, but also upon the maggots. Minute wasps will arrive to parasitize the maggots. Tiny flies, whose very existence remains unguessed by most people, will similarly arrive at various stages of decay and will leave tell-tale signs of their visits. Myriads of other creatures will arrive at various times, each to leave its mark for future interpretation by those who look into such things. On the basis of the fact that anything that changes with time can be used as a clock, the succession of insects occurring on a dead body can, in principle, be exploited as a measure of time since death.
This intriguing idea has an important application, for it can help to answer one of the most basic questions asked during a murder investigation: 'When was the crime committed?' Although this is one of the commonest questions a policeman is likely to ask himself when investigating a murder, it is also one of the most difficult to answer. Contrary to popular belief, based on so many crime stories and whodunnits, the doctor who attends the scene is usually quite unable to say anything very useful about time of death, except in certain special circumstances. The whodunnit medico, who says things like: 'Inspector, the murder took place at a quarter to two on the morning of Tuesday 23rd March', is a totally fictitious character.
In real life, forensic pathologists (medics whose expertise lies primarily in the determination of cause of death) can offer an opinion on time of death only during the first three days or so after a crime is committed. Forensic pathologists exploit three natural phenomena to help them answer the question of time of death. These are the onset and passing away of rigor mortis; the time taken for the temperature of the body to drop to that of the surrounding air; and the order in which the various organs start to decompose. All these changes take place and are over within two or three days of death; beyond that time there is no easily measurable pathological change that can be used to determine when the victim died.
But it is not only in the matter of time of death that insects can help in criminal investigations. They can also help us to discover thesite of the crime and how it was committed. They can tell us whether someone was a victim of blackmail; whether a crime was committed with malice aforethought; and whether someone's death was a suicide. They can shed light on crimes involving the smuggling of drugs; they can lead us to the home town of a murder victim; they can help us to identify a rapist; and many other things besides.
Curiously, the use of insects in the investigation of crime is a relatively new subject. Like most of forensic science, it began to take shape during the second half of the nineteenth century but, even today, very few people, including some police officers, know that it exists at all.
* * *
Sir Arthur Conan Doyle, the creator of Sherlock Holmes and Dr Watson, was a pioneer forensic scientist. It was he who introduced the idea of taking plaster casts of footprints. His Sherlock Holmes stories, which emphasize the central importance of physical evidence in criminal investigations, were actually used as instruction manuals by the Chinese and Egyptian police forces for many years, and the French Sûreté named their great forensic laboratory at Lyon after him. He transformed the very way criminal investigators thought about their work. We owe him a great debt of gratitude.
For a long time I believed that Conan Doyle, in spite of his great understanding of forensic matters, overlooked the evidence of the ever-present insects. In one of his short stories, Black Peter, in which a sailor, Captain Peter Carey, is murdered with a harpoon and pinned to the wall, Conan Doyle has Inspector Stanley Hopkins describe the scene of the murder to Sherlock Holmes in the following way:
'Well, I have fairly steady nerves, as you know, Mr Holmes, but I give you my word that I got a shake when I put my head into that little house. It was droning like a harmonium with the flies and bluebottles, and the floor and walls were like a slaughterhouse ... And there in the middle was the man himself, his face twisted like a lost soul in torment, and his great brindled beard stuck upwards in his agony. Right through his broad breast a steel harpoon had been driven, and it had sunk deep into the wood of the wall behind him. He was pinned like a beetle on a card. Of course, he was quite dead.'
In the conversation that follows, Holmes rebukes the young inspector for failing to notice any footmarks, saying, 'My good Hopkins, I have investigated many crimes, but I have never yet seen one which was committed by a flying creature.' Hopkins is contrite but, if he had had his wits about him, he might have retorted that although no flying creatures committed the crime they certainly arrived to bear witness to the event. For Sherlock Holmes totally ignores the presence of the flies and bluebottles, which were clearly inserted by Conan Doyle purely for dramatic purposes, not as evidence that could have been used to solve the mystery.
Ever since I first read this story many years ago, I have wondered whether Conan Doyle really could have overlooked the significance of the flies. Although Sherlock Holmes does not discuss them as evidence in Captain Carey's murder, their presence confirms the account of events given by various characters in the story. In fact, the description of the scene is so uncannily realistic that I have to conclude that Conan Doyle must have known something about the habits of flies. Let me explain.
At about 2 o'clock in the morning, Captain Carey's wife and daughter heard a loud bellow coming from the Captain's hut in the garden. They thought nothing of it, since the Captain often roared and bellowed when drunk. It was only at noon that someone went to the hut to investigate, since the Captain could be very violent when under the influence of alcohol, and it was then that his dead body was discovered, with the flies swarming around it. Within the hour, Inspector Hopkins was at the scene.
Ten or eleven hours had elapsed since the murder, which must have taken place when the Captain uttered his 'fearful yell' in the night. Under the prevailing conditions – it was the height of summer and the murder had taken place at night – the swarms of flies and bluebottles witnessed by Inspector Hopkins at about 10'clock in the afternoon are exactly what one would expect to see. The time delay is quite accurate. Furthermore, Hopkins told Holmes that he had followed the master detective's methods and made a thorough examination. Yet he reported no fly eggs on the body; again, this is exactly what one would expect after the given period that had elapsed since death. This is because flies will be attracted to a body, but not lay eggs on it until the conditions of decomposition and temperature are exactly right. The flies would probably have been just about ready to lay their eggs.
Flies are not normally active at night, not because it is dark but because the temperature is low. It is only during the day, when the air temperature rises, that they become active. Flies also avoid laying eggs on a body whose temperature has not dropped to a certain acceptable level. Finally, the odours of decomposition that attract flies take some hours to emanate from the body. Conan Doyle's description of the murder scene is convincing in every detail.
* * *
Flies and bluebottles are among the very first arrivals at the scene of a murder. If, like King Solomon, we could talk to insects and other animals, flies, as well as their maggots (so often found in the body of a murder victim), would be the most valuable of witnesses. Alas, we cannot talk to them, but we can do the next best thing, which is to study their habits, allowing us to draw conclusions based on our understanding of their nature.
The very simple fact that bluebottles and other blowflies will so often lay their eggs on the bodies of murder victims has very useful consequences in murder investigations. When the maggots hatch from the eggs and start feeding on the tissues of the body, they will, of course, grow and change as they age. If the age of the maggots in a body can be determined, this will give a very good idea of time of death, since the maggot cannot have been alive for a longer period than the body has been dead. Of course, the murder victim may have died some time before the flies arrived to lay their eggs, so the age of the maggot will give us a minimum time since death, not an actual time of death. In other words, it can give us a time by which death had occurred. However, this does not mean that we cannot often give an estimate of the actual time of death, based on evidence other than the age of the maggot alone.
There is much more truth in the rhyme about Cock Robin than the anonymous author ever knew, but I am convinced that the early arrival of flies at a dead body must have inspired that first verse.
* *
I have practised in the field of forensic entomology – the application of insect biology to the investigation of crime – for over twenty five years. I have many memories of those years, some pleasant, others not. Nevertheless, the general experience I gained has taught me a great deal about humanity, justice, science, law and, of course, insects. The world of flies, maggots, beetles and bugs opened up a much wider and more human world.
I am often asked what it is like to be a forensic scientist. The question carries with it an assumption that the forensic science profession is one that can be described as 'glamorous'. In truth, I have not found it so. However, I have always felt that the scientific investigation of crime is very interesting work, but being interesting is not its only attribute. As a forensic scientist one has to visit the seediest of dwellings at the most unsocial of hours. Often, one finds oneself trudging across a muddy field early on a cold, wet morning or carrying out a postmortem examination late at night. Waiting for interminable hours at police stations; being ferociously cross-examined by hostile barristers in court; dropping everything at a moment's notice to go to the scene of a crime; all these things have their interesting aspects, but they are usually not immediately apparent.
In spite of these somewhat negative features, forensic science is often very exciting, even exhilarating. The interesting scientific discoveries that can be made, the knowledge one gains, the insights that help with future investigations, make it all well worthwhile. But the greatest reward is the knowledge that one's findings have actually made a difference, that they enabled justice to prevail. It is a great pleasure to be told, at the end of a trial, that one's testimony was crucial to the understanding of the case.
But one must not forget the ever-present possibility of failure, that one may be mistaken. The very thought that one might have given incorrect interpretations of the evidence, however honestly, is a haunting one. I remember one occasion, early in my career, when I lay awake all night, worrying that I might have misled the jury. I went over and over the evidence in my mind, trying to reassure myself that I had said nothing that could have led to a miscarriage of justice. The next day I travelled north to meet the pathologist in the case and go over my conclusions with him, just to make sure that I had been as rigorous and objective as possible. I need not have worried, since all the other evidence confirmed my conclusions but, despite the ugliness of the thought of error, it is a concern that should never be far from the mind of the forensic scientist. Oliver Cromwell's exhortation – 'I beseech you, in the bowels of Christ, think it possible you may be mistaken' – is very wise and should be engraved on the hearts of all who are involved with the administration of justice.
My forensic work has brought me into contact with other forensic scientists, with police officers, barristers and solicitors. Some were good, some bad, some indifferent, but I must express my gratitude to them all, without exception, for I have learnt something from the best and from the worst of them. Many have shown me great kindness and it is on this more positive aspect that I will concentrate in the following pages. My name not being of a kind that is easily articulated by the English tongue, I have become known to the police (sinister expression!) as Dr Zak. But the highest accolade I have ever received from them came from Superintendent Clive Jones of the Dyfed-Powys Police, who dubbed me 'the Maggotologist'. When I came to hear of this he asked me whether I minded being so called. I said that I certainly did not and was in fact immensely flattered. As far as I know, I am the world's only holder of this august title!
Nevertheless, my experiences have shown me that there are great deficiencies within the criminal justice system, the police and the practice of forensic science. It is not possible to be involved in the investigation of crime and remain unaware of and unaffected by these flaws. It follows that a book like this cannot be complete without some comment on these matters.
* * *
Let us go back to insects, those wonderful creatures that form the connecting thread of this book. How can they help us to solve crimes? To many people, the very idea that insects can contribute to a murder investigation seems absurd. I was once told about a conversation that took place in a pub near which a murder had been committed. I had been involved in the investigation. One of the wags in the pub told the others that word was going around that 'they' had found out when the murder took place by asking a maggot! Worse still, many people seemed to believe the story! This chap could not believe how gullible people could be. He was quite dumbfounded when he was told that the story, in essence, was true!
Insects can help us to understand what happened in criminal cases because they are found almost everywhere, with the exception of the sea, where only a few species occur. On land and in freshwater, insects are the most abundant of animals, forming over eighty-five per cent of the world's known species. Well over one million species are known and new species are discovered almost every day. The total number may well be somewhere between ten and fifty million species. One witty Oxford professor once said that, as a rough approximation, all animals are insects!
Insects are found on every continent, including Antarctica. It is their ubiquity and large numbers, both in terms of species and individuals, that make them so useful in forensic investigations. The best way to explain why this is so is to invite you for a walk through a garden in spring.
As you walk along the path, looking at the flowers in the borders, you will see a number of different kinds of bumble-bee. Some are small and yellow, others are large and black with red tails, while others have white tails, and so on. You move on and come to an apple tree. Buzzing around the apple-blossom are various insects, most of which look like bees, but a closer examination will reveal that some are wasps and others are delicate black-and-yellow flies. You make your way down to the bottom of the garden where there is a compost heap; prodding it with the toe of your shoe, a swarm of minute, nondescript flies rises into the air. All these little black or grey flies look much the same to you but, in all probability, there will be several different species in that small swarm.
What does all this have to do with forensic investigations? When you walked around the garden, what you saw was a large number of insects exploiting particular sources of nourishment. The bees on the flowers, the various insects on the apple tree, the small flies in the compost heap. Several species were all trying to exploit the same resource. Now, classic ecological theory suggests that no two species do exactly the same thing in nature because, if they did, they would inevitably have to compete with one another to the detriment of both. Therefore, species that are very similar and closely related tend to evolve life-styles that are slightly different from one another. The different bumble-bees visiting the flowers in the border were attracted to different flowers or to different parts of the same flower; the insects on the apple tree were feeding on the apples themselves or on the tree's sap; and the little flies in the compost heap were each breeding or feeding on different components of the rotting vegetation, or even parasitizing different creatures living in the mound.
(Continues...)
Excerpted from Maggots, Murder, and Men by Zakaria Erzinçlioglu. Copyright © 2000 Y. Z. Erzinçlioglu. Excerpted by permission of St. Martin's Press.
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