All That Remains: A Renowned Forensic Scientist on Death, Mortality, and Solving Crimes

by Sue Black

There are seven recognisable stages of postmortem alteration. The first is pallor mortis (literally, ‘paleness of death’), which starts within minutes and remains visible for about an hour.

As the heart ceases to beat, capillary action is halted and blood drains away from the skin surface and begins to settle at the lowest gravitational level within the body.

The second stage, algor mortis (‘coldness of death’, or the death chill) follows quickly as the body starts to cool down (in some instances it may warm up, depending on the ambient temperature). The temperature of the body is best recorded from a rectal reading as the skin surface will generally cool, or heat up, more quickly than the deeper tissues.

it cannot be assumed that the temperature of the body was normal at death. Many factors can influence core temperature, including age, weight, illnesses and medication.

Within a few hours of death, muscles start to contract and the third and temporary postmortem condition, rigor mortis (‘stiffness of death’), will set in. Rigor starts in the smaller muscles first, usually inside five hours, and then spreads to the larger muscles, peaking between twelve and twenty-four hours postmortem.

When we die, the pump mechanism that keeps calcium ions out of the muscle cells ceases to operate and calcium floods across the cell membranes. This causes the actin and myosin filaments within muscle to contract and then lock, shortening the muscle.

Other factors that will have a bearing include some poisons (strychnine hastens the rigor process, whereas carbon monoxide slows it down). Rigor is also brought about more quickly by intense physical activity before death and may never take place in cases of cold-water drowning.

With the heart no longer pumping, the body enters the fourth phase of postmortem alteration, livor mortis (‘blue colour of death’). The blood will have begun to pool at the lowest gravitational level of the body almost immediately after death, at the pallor mortis stage, but lividity may not be visible for a couple of hours.

Where the skin comes into contact with a surface (for example, if the body is lying on its back), blood is pushed out of the tissues into adjacent areas where there is no contact pressure. So the contact areas will appear paler compared to the darker surrounding areas of lividity.

A body with marks of lividity on its back, but found lying on its face, has clearly been turned over. If someone has died by hanging there will be a pooling of blood in the lower segments of all four limbs and this fixed-lividity pattern will remain in the distal arms and legs even after the body is cut down.

If a body remains undiscovered through these four phases it will begin to smell pretty bad. In the fifth or putrefactive stage, the cells start to lose their structural integrity and their membranes begin to break down due to the slight acidity of the body fluids. This is called autolysis (literally, ‘self-destruction’) and provides the perfect conditions for anaerobic bacteria to multiply and start to consume the cells and tissues.

This process releases a variety of chemicals, including propionic acid, lactic acid, methane and ammonia, whose presence can be used to detect where a decomposing body has been hidden or buried.

Dogs are not the only species with a highly developed sense of smell: rats have also been trained to respond to the odours of decomposition as, incredibly, have wasps.

Active and advanced decay, the sixth stage of decomposition, will be set in motion when the larvae hatch and maggot masses take full hold.

The process generates a huge amount of heat: a maggot mass of around 2,500 can raise temperatures to some 14°C above the ambient temperature. Beyond 50°C the larvae will not survive, so when the core of the maggot mass approaches this critical temperature, they will separate and break into smaller and smaller clumps to try to cool down.

The seventh and final stage is skeletonisation, where all the soft tissues of the body are lost, leaving only the bones, and possibly some hair and nails, which are made of inert keratin. Depending upon the environmental conditions, and with the passage of enough time, even the bones may be destroyed.

how long does this after-death disintegration process take to complete? There is no simple answer. In parts of Africa, where insect activity is voracious and temperatures high, a human body can be rendered from corpse to skeleton within seven days. However, in the cold wilds of Scotland it might take five years or more.

Freezing can stop decomposition almost completely and as long as the body doesn’t thaw out too many times, recognisable features may remain for centuries. At the other extreme, dry heat, which dehydrates the tissues, can also preserve a corpse.

Chemicals are largely responsible for the prolonged preservation of the famous mummies of Egypt such as Rameses and Tutankhamun. Here, removal of the internal organs and the packing of the body cavities with herbs, spices, oils, resins and natural salts, such as natron, were highly skilled procedures.

Submersion in water, as in the case of bodies found preserved in peat bogs, can halt aerobic activity. The body becomes sterile, and in time the acidic nature of the peat dissolves away the skeleton, leaving behind the tanned leather skin, which may remain almost visually recognisable, even after centuries have passed.

In the right conditions – temperature, water pH and oxygen levels – the fat in the body can, instead of putrifying, saponify and turn into adipocere, also known colloquially as grav...

‘Brienzi’, a headless male body fully encased in adipocere, was found floating in a bay of the Brienzer See in Switzerland in 1996. Analysis finally determined that he had drowned in the lake in the 1700s and his body had become covered in sediment. Two weak earthquakes in the area might have been sufficient to e...

Our name – the very core of what we consider to be ‘me’ – can survive long after even our bones are gone, commemorated perhaps at our final resting place on a headstone, plaque or in a book of remembrance. It may be one of the least permanent constituents of our identity, yet it can outlive our mortal remains by centuries,

A nameless body is one of the biggest problems for any police investigation into a death, and there is always an imperative to resolve it, regardless of how much time has elapsed between the death and the discovery of the body. Forensic scientists will attempt to link the physical remains with a name so that documentary evidence can be accessed, relatives or friends found to confirm the identification and the circumstances surrounding the death explored.

Given the number of people who are reported missing every year – approximately 150,000 in the UK alone – it is no easy task. At its most basic level, our mission is to try to reunite a body with the name it was given at birth.

When you factor in nicknames and abbreviations, one person can be known by a staggering array of labels. My own case is not untypical. I was born Susan Margaret Gunn. As a child I was Susan – or Susan Margaret, the full Sunday name, when I was in trouble, which was quite often. As I grew up my friends called me Sue. I married and became Sue MacLaughlin (Mrs, later Dr); then, on my remarriage, Sue Black (Professor, later Dame) – and for a very short time, to maintain publication continuity for my career, I was Sue MacLaughlin-Black (talk about an identity crisis).

Since unique names are rare, most of us will share our most personal label with many others. Of over 700,000 Smiths in the UK, some 4,500 of them are called John. My own maiden name is not particularly common: last time I checked, there were only 16,446 fellow Gunns registered in the UK, most of them, not surprisingly, in the very north-east of Scotland around Wick and Thurso. Only about forty were called Susan.

Such themes are a feature of most of Shakespeare’s comedies; indeed, much of his work deals with the concept of identity in one way or another.

Since our identity is built throughout our lives on the foundations laid down by those around us – those we trust to tell us the truth – our name and our heritage become the bedrock of our sense of self and our security. It can prove to be a house of cards. When a lie is exposed, everything we believe about ourselves and our place in the world can tumble down around our ears.

So when forensic anthropologists are faced with an unidentified body, how do we go about reuniting the deceased with their name? First we need to establish a biological profile: was this person male or female? How old were they when they died? What is their ancestral origin? How tall were they? The answers to these questions allow us to place an individual into a specific pigeonhole.

One search performed for a white male, aged twenty to thirty and between 5ft 6ins and 5ft 8ins in height, returned 1,500 potential names in the UK alone.

There are three features recognised by the International Criminal Police Organisation (INTERPOL) as primary indicators of identity: DNA, fingerprints and dentition.

There is a common misconception that the recovery of DNA from a body will in itself always lead to a positive identification. But of course a comparison must be made, either with a source sample of the DNA of the person the deceased is suspected to be, if there is one on record, or with samples provided by direct family members (parents, siblings or offspring). The genetic link with a parent’s DNA would be equally as strong in, say, an estranged brother of the deceased, so if a family source is to be used it must be supported by other features of biological evidence specific to the missing person, such as their dental records.

When testing parents, we prefer if possible to use a mother’s DNA, as obviously there can be some doubt as to whether Dad is the natural father.

There was one unidentified, badly fragmented body in the mortuary that fitted this man’s general physical description, but the DNA did not match that of his sisters. Investigation would later reveal that the body was indeed their missing brother. Unbeknown to them, and perhaps to him, he had been adopted as a baby – a secret that was eventually confirmed by an elderly aunt.

UK police forces receive, on average, 300,000 calls relating to missing persons every year – nearly 600 reports a day. About half of this number will go on to be officially recorded as missing, of which around 11 per cent will be classified as high-risk and vulnerable. Over 50 per cent will be between the ages of twelve and seventeen and many of these will fall into the ‘absent’ or ‘run-away’ category. A small majority (about 57 per cent) will be girls. Mercifully, many children return or are found alive but more than 16,000 will remain ‘lost’ for a year or more.

around 62 per cent are men, most commonly between the ages of twenty-two and thirty-nine, and of the 250 or so people a year found dead in suspicious circumstances, fewer than thirty are children.

When someone goes missing, INTERPOL posts what are called ‘yellow notices’ across its 192 member countries to alert their police forces. ‘Black notices’ are issued when a body is found and cannot be identified. In an ideal world, all the black notices would correspond to a yellow notice. We attempt to match them by comparing features of identity from the missing person (antemortem) with those of the deceased (postmortem).

Most countries do not have universal records of the DNA or fingerprints of the general population and there is no nationwide database for dental records. So unless you are in the police, the military or have been previously convicted of a crime, it is highly unlikely that your identifying features will appear on any database.

white male between twenty and thirty years of age, 5ft 6ins to 5ft 8ins in height. From his skeleton, we were able to identify some old injuries that had fully healed by the time he died: fractures to three of his ribs on the right-hand side; a fracture of the right collarbone and another to his right kneecap. If all these injuries were sustained in the same incident it was highly likely that he would have been treated at a hospital and there would be medical records. He’d also had four teeth taken out, the first premolar on each side from both the upper and lower jaws. The drift of the remaining teeth showed that these were unlikely to have been congenitally absent but had been removed professionally. Somewhere, then, a dentist would have records of these specific extractions. But we would have to find them. It was these basic characteristics that generated those 1,500 potential identities.

The news we bring to relatives is rarely happy, but we believe it is delivered with a kindness, honesty and respect that will ultimately help to set in motion a coping and healing process.

We view our identity as being intimate to us but in reality, we share its finer details with everyone with whom we interact. And every now and again someone acting in an official capacity will want you to share it with them – in our case, when you are no longer alive.

Uncle Willie died in a way that would have made him laugh just as heartily, had he been capable of it. One Sunday, at our house for lunch, he just slumped at the table, as if suddenly dropping off to sleep. He had suffered a ruptured aortic aneurysm, something that strikes without warning – a mercifully instantaneous death for him but a brutal shock for my rather emotional and sensitive mother. One moment he was his usual jolly self and the next he was gone. Unfortunately for Uncle Willie, and for my mother’s tablecloth, he collapsed rather inelegantly, face first, into his bowl of Heinz tomato soup.

The changes brought about in the appearance of a human body are more profound than can be accounted for simply by the cessation of blood flow and loss of pressure, the relaxation of muscles and the powering down of the brain. Something quite inexplicable is lost – whether we choose to call it a soul, a personality, humanity or just a presence.

Fear of death is often a justifiable fear of the unknown; of circumstances beyond our personal control which we cannot know and for which we cannot prepare. ‘Pompa mortis magis terret, quam mors ipsa,’ the philosopher Francis Bacon wrote over 400 years ago, quoting the Roman Stoic Seneca. ‘It is the accompaniments of death that are frightful rather than death itself.’

It is pointless even to try to control that which cannot be controlled. What we can manage is how we approach and respond to our uncertainties.

given that over 153,000 people die every day on this planet, I suspect that the sample size of those who have ‘come back’ doesn’t reach statistical significance, and no further real scientific understanding has been gained from such cases.

Vivid imagery, false memories and the replaying of real scenes from the past can be induced by fluctuating levels of the neurotransmitter dopamine, which interacts with the hypothalamus, amygdala and hippocampus. Depletion of oxygen and increased levels of carbon dioxide can cause the visual hallucination of bright light and tunnel vision, as well as a feeling of euphoria and peace.

Maybe some people would consider it disrespectful to belt out ‘The White Cliffs of Dover’ and ‘Ye Cannae Shove Yer Granny Aff a Bus’ round your mother’s deathbed,

Wait that second one

The American counsellor Lois Tonkin reminds us that loss isn’t something we ‘get over’, and it doesn’t necessarily lessen, either. It remains at the core of us and we just expand our lives around it, burying it deeper from the surface.