How to Write Crime Fiction – Part Six: Forensics

As a writer, getting the crime scene and the procedural of the police right is obviously a priority for your novel. In this section we look at ways and means of getting the forensics right and how, police divisions within the UK and how to kill off your characters.

Here is an extract from Stone Dead where the detective investigates the scene of a murder. Note how the forensic details come into play through the narrative’s progression.

DC Dave Thomas parked the car at the end of the cul-de-sac and sat for a moment with the driver’s window wound down, looking for his notebook and listening to the sound of a train as it clanked its way slowly through Parson Street railway station. The air was humid and smelt of cooked breakfasts and discarded takeaways. He glanced in the rear view mirror. The street was quiet except for a couple of youths kicking a football about at the far end of the street. So engrossed were they in their game that they hardly noticed him. Both wore the uniform he had come to associate with the youth of the impoverished area: the dreadlocks, black power T-shirts, the hipster trousers and Doc Marten boots. He wound up the window, then got out and locked the car. Best to be on the safe side.

He made his way past overgrown gardens until he drew level with the front door. It lay slightly ajar. From inside he could hear a baby crying and there was a smell of burning food. He knocked loudly on the paint-peeled door and waited, but there was no reply. He pushed the door wide, stepped inside and called again, this time louder.

“Michelle Brown?”

Still no answer. He carried on slowly down the hallway, alert, cautious. Something wasn’t quite right. He could sense it. Smoke was coming from the kitchen. He opened the door. A pan was alight on the hob. He grabbed a tea towel, wrapped it round the handle and dropped it into the sink, then turned off the gas. The baby’s wailing grew louder. It was coming from one of the rooms upstairs. He was about to climb the stairs when he noticed a shape through the crack of the living room door. He was about to enter when he saw the bloody footprint at the entrance. Elongated blood spatters on the wall of the hallway confirmed his worst suspicions.

He took a handkerchief from his pocket and pushed the door open. The body of Michelle Brown lay face down, the dark hair matted with blood. He knelt down, careful to avoid the crimson pool which seeped from beneath her.

The mouth lay open, the teeth broken and bloody, the nose smashed to a pulp. He felt for a pulse in the neck but there was none. The flesh was still slightly warm. He looked at his watch. 11.30am. He made a mental note of the time. He stood up again. Dripped and expirated bloodstains on the textured carpet and on the edge of the skirting board. Impact spatter on the wall by the standard lamp along with a small void, indicating Michelle’s attacker had stood over her to deliver his final, lethal blows. He followed the carpet towards the door. A smudged, half print of a left foot. Another smaller smudge of blood on the door handle, possibly a print. On the wall adjacent to the door was a series of low velocity spatter stains with projections, indicating the killer’s movement towards the back door, showing where the blood had dripped from his hand and the murder weapon.

Keeping to the edge of the hall carpet, he made his way to the back door and, finding it open, knelt down to examine the handle. Another set of prints, a thumb and forefinger this time, very clearly defined.

In the back garden he looked round for a possible murder weapon but the space was almost bare of debris. He noticed a small garden shed, adjoining a low fence. Beyond it was an alleyway.

He peered over the fence. Another footprint, and on the fence, a fresh splinter where the killer’s jacket or trousers had snagged. He picked up a small stick and carefully levered the shed door open. The sunlight streamed in through the opaque window, picking out a rusting lawn mower, a broken broom and two bags of compost. Then he spotted it. On the floor a short piece of lead pipe, one end smeared with blood.

He walked back up the path, entered the back door and again heard the baby. It gave a long sustained wail of sorrow. He was torn between comforting the child and returning to the car. He decided on the latter. He must be quick about it and then secure the murder scene and wait for forensics.

Stone Dead

How to Kill off your Characters

The investigation of a crime is a highly professional and scientific procedure. The technology is complicated, but the concern of the writer is more with the results than with the nature of the tests: you need to know what your detective may expect from the pathologists and the forensic laboratories.

Choose your Weapon

Blunt Instruments

Almost any object, from a walking stick or a brick in a sock to an electric iron or a hammer, can be a blunt instrument. All the term implies is that the weapon does not have a sharp stabbing point or a cutting edge.

The problem from the murderer’s point of view is that the blunt instrument may not kill at the first blow. Further blows can be extremely messy, even if the victim is unconscious.

The detective will find plenty of traces at the scene of the crime, on the weapon itself, and on the clothing of the perpetrator. Within the wounds, there are likely to be traces of anything with which the weapon has been in contact – for example, traces of grease of a piece of garage equipment. The shape and depth of the wounds will indicate the type of instrument used.

Knives and Axes

The nature of the wound indicates the type of weapon. An incised wound, made with a razor or scalpel, is longer than it is deep or wide. A stab is greater in depth than in length or breadth.

Killing by stabbing is not difficult once the skin is penetrated. The knife is not, necessarily, a long one: the elasticity of the skin will permit considerable penetration by a small blade. The bleeding may be almost entirely internal.

Sometimes stab wounds produce strange results. Death from a fatal blow may not ensue immediately; victims have been known to walk away from the scene of the crime before collapsing.

Slashes and axe attacks generally produce a good deal of external bleeding. If the victim gets a chance to fight back, there will be defence wounds on hands and arms.


Poison obtained from wild plants such as foxgloves, fungi, deadly nightshade, and hemlock is the classic method of murder down through the centuries. Until modern times, the crime went virtually undetected.

The most famous murder trials of the nineteenth century featured cases of arsenical poisoning, and there have been notable instances in modern times. Arsenic is easily detectable, and the traces remain in the corpse for a long time.

Another old favourite is cyanide, once used for rat poison and insecticide, now strictly controlled but used in industrial processes and agriculture. Cyanide comes in many forms, the best known being prussic acid and hydrogen cyanide gas. The most accessible are the alkaline cyanides, especially potassium cyanide.

Strychnine is the third `Victorian’ poison. It was, and still is, used in medical preparations as well as in animal poisons. It has a very bitter taste, and the symptoms are easily recognised.

A modern poison is paraquat, used to suppress weeds. There is no known antidote.

With the expanding use of drugs, both medical and illegal, the opportunities for unsuspected crime have increased. Suicides overdose on barbiturates. The problem for a murderer would be that of persuading the intended victim to take them. Crushing them up and adding the powder to food or drink would be unlikely to work, since the taste would be overpoweringly horrible even when disguised with sugar.

With all poisons, the question of dosage arises. People have differing levels of tolerance to poison. A doctor or pharmacist would know how much to give, while a layman would be inclined to overdose.


The general public has only limited access to rifles and pistols. The criminal fraternity has its own suppliers of illegal shooters. These are not ‘registered’ weapons, and are likely to be broken up once they have been fired. Shotguns come into a different category. They are available everywhere, and certificates for the holding of them are routine; rural areas are full of them. Criminals shorten the barrels and the stock to turn a shotgun into an overgrown handgun. The result is a fearsome weapon, useful as a menace, but not accurate except at close range, when it will inflict a very nasty wound.

All weapons except shotguns have parallel grooves carved in spirals on the inside of the barrel to stabilise the bullet and keep it on its trajectory. Size goes according to the internal diameter of the barrel. Shotguns use cartridges which contain pellets to form a spread when fired. Shotguns are ten-, twelve- or sixteen-bore, an archaic classification based on the number of solid lead roundshot to the pound.

Firearms leave marks, individual to each weapon, such as rifling on a bullet or marks of the firing-pin on the cartridge case, for the forensic scientist to find. Automatic pistols will also leave marks from the ejector, magazine, bolt-face, chamber-wall and extractor.

Different types of firearms have different characteristics:

Rifles – accuracy to about 2000 yards using high-velocity bullets; military rifles are mostly automatic and light-weight. An example is the AR-15 Armalite, firing 800 rounds per minute of 5.66mm ammo, magazine holding 30 rounds; snipers use heavier rifles with more sophisticated sights, including infra-red and laser. These are bolt-action, hand loaded, with extra-long barrels.

Pistols – revolvers hold rounds (usually six) or cartridges, and are very reliable. Examples are: calibres .22, .38 (standard US police issue), .357 (magnum, also used by police), .44. Automatics have a complicated mechanism which has a tendency to jam; magazines hold up to thirteen rounds and are fired by single pull on trigger. An example is the Walther 7.65 mm.

Machine-guns – all automatic, professional military weapons, are used by terrorists, but rarely by ordinary criminals. An example is Ingram M-10, with a fire-rate about 1,200 per minute and a magazine holding 32 rounds.

Shotguns – weapons with a short range of up to 80 yards, designed for shooting of game in motion. They are mostly double-barrelled; the single-barrel semi-automatic pump action is not widely used. Capable of killing a man at close-range.


In real life, hangings are usually suicide or accident. There have been cases where a ‘hanging’ has been staged to cover up a murder, but the truth is always revealed when the rope is removed from the neck, genuine hanging leaving a deep bruise on the flesh at the point of pressure. Anything put round the neck after death would not normally show much of a mark. Death in hanging attempts is frequently due to cardiac arrest.


Asphyxiation occurs when the air supply to the blood is cut off, starving the tissues of oxygen. This is done in a number of ways:

Suffocation – the supply of oxygen in the air is dangerously reduced or cut off by the presence of smoke, dense dust, smog, or unbreathable gases.

Smothering – the external blockage of the nose and mouth. A pillow placed over the face of a child or old person will kill, but this is less likely to succeed in the case of an adult. A plastic bag placed over the head will kill very quickly.

Choking – due to an object wedged in the windpipe, or a gag rammed into the mouth, causing an accumulation of saliva and mucus if left too long in place. Death occurs even though the nostrils are free.

Manual strangulation – a frontal attack, causing fracture of the larynx and hyoid bones. A right-handed assailant will leave a thumb bruise on the right side of the victim’s neck, and finger bruises on the left.

Strangulation by ligature – an attack from the rear, using almost anything as a ligature, and less likely to fracture the bones of larynx and hyoid. The ridges of the ligature will show up as curves on the neck, giving no true indication of its width.

Most strangulations contain an element of cardiac arrest, as pressure on the carotid arteries cuts off the supply of blood to the brain. A sudden grabbing of the neck may produce the same effect. Traumatic asphyxiation comes from restriction of the breathing movements of the chest. The only known case of it as a murder method is that of the body- snatchers, Burke and Hare, who are supposed to have killed their victims by sitting on their chests.


The victim dies of asphyxiation, but not with lack of oxygen as the main cause; it is the result of the fluid and chemical disturbances which take place in the blood that kills. This can occur rapidly.

Drowning in fresh water is quick — a matter of about four minutes. As soon as someone falls — or is pushed — into a lake or river, the immediate reaction is struggling and panic, and water is taken into the lungs, and into contact with the breathing membrane through which, to support life, air normally passes. The water passes through the membrane into the blood. Fresh water has not the same osmotic pressure as the blood; it increases the volume of the blood rapidly and dilutes it, upsetting the biochemical balance of the body. Death is inevitable.

Drowning in sea water gives the victim a better chance of survival if they are fished out. Salt water has the same osmotic pressure as the blood, so no massive fluid transfer takes place, although the level of sodium chloride (salt) rises. Death does not usually take place in under eight minutes, and may be up to twenty minutes.

The temperature of the water is important in drowning. Reflex cardiac arrest can take place on falling into water, especially if it is cold. Equally, a sudden douche of cold water against the back of the nose or throat can cause instant unconsciousness and death if the victim is not resuscitated quickly enough.

Murder victims are often disposed of by throwing the body into water. By natural processes, an immersed body will rise, sooner or later. Weighting down can prevent this, or merely serve to delay discovery, and so present the pathologist with a most unpleasant corpse. If decomposition is far advanced, it may prove impossible to determine the cause of death. Identification also may present serious problems.

Distinguishing between a body which has drowned and one which was dead when it entered the water is not so difficult. The signs of drowning are: fine froth in the air passages and lungs; debris in the air passages; cadaveric spasm of the fingers, retaining hold of underwater weeds clutched at in the panic of drowning; the presence of microscopic water algae (diatoms) pumped round by the heart into the organs of the body in the last moments of life. A dead body dropped into water will have water in the lungs, and diatoms there, too: but the diatoms will be nowhere else.

Divisions Within the UK Police Force and How They Operate

Unless you have chosen a closed setting, such as an island with no communication with the mainland, or a house cut off by snowdrifts, sooner or later, you will have to sketch in some details of the officials who uphold law and order. Police investigations will impinge upon the activities of other characters, even if your detective is an amateur. You need to know how the police work.

The British Police System

In police terms, the United Kingdom is divided into Regions each made up of a county or a group of counties, depending upon the density of the population, which reflects in the crime rate. Within the Region, each county has its own police force, divided into Divisions and then into Sub-Divisions, each centred on one of the towns. The Metropolitan Police District (MPD), Headquarters at Scotland Yard, is divided into eight areas, and combines with the City of London Police to form a separate Region.

Police Command Structures


Metropolitan Police District
The Commissioner
Assistant Commissioners
Deputy Assistant Commissioners
(1 to each area) Commanders
(2 to each area)

The City of London Police is commanded by a Commissioner. Subordinate ranks of both the MPD and the City of London Police are the same for the rest of the country — Chief Superintendent, Superintendent, Chief Inspector,
Inspector, Sergeant and Constable.
Regions (outside London)
Policing is carried out by the police forces of the various counties to form the Region. Overall command is from Regional Headquarters.

Regional Headquarters

Chief Constable
Deputy Chief Constable
Assistant Chief Constables
Chief Superintendents i/c HQ Departments
Traffic & Communications
Personnel & Training
Operations (HQ Control Room)
CID (DCS i/c, Deputy and Scenes-of-Crime specialists.
No operational detectives. DCS or Deputy takes charge
of all major crime investigations in Region)
Each county force is divided into territorial Divisions.

Divisional Headquarters

Chief Superintendent
Superintendents or Chief Inspectors


Uniformed Police
CID (Crime Squad, Incident Room)
Territorial Divisions have Sub-Divisions, and, at the bottom• of the scale, Section Stations (in very small towns)
Superintendent, Chief Inspector
or Inspector

Uniformed Police

CID (Inspector i/c)
Section Stations
Detective Sergeant or Constables
Uniformed Constables

Civilian Staff

Civilians are employed for many secretarial posts. There is a Civilian Establishment Officer at Regional Headquarters, also a Welfare Officer, and a Press Officer. Increasingly, civilian experts are employed in scenes-of-crime investigations.
Regional Serious Crime Squads
Certain Regions have established Serious Crime Squads. These are not to take over the work of the CID; their function is mainly the collection of intelligence and investigation of major criminals, including those dealing in drugs.

Some Words About Criminal Profiling

Profiling and Serial Killers

Despite what you might read in Val McDermid’s novels, profiling in real life is a pale shadow of its fictional counterpart. The theory of profiling was first developed in Britain by Dr David Canter, who built on the approach of the FBI’s Behavioral Analysis Unit. That unit was staffed by investigators rather than psychologists and, according to Dr Canter, used a pragmatic rather than academic approach to profiling, relying on their intuitive interpretation of every case based on their experience rather than developing a set of principles that could be applied to any case.

The attraction of profiling is that it gives the investigator a picture of the criminal thus enabling the search for a suspect to be limited in some way — e.g. where he or she lives and works, any criminal history, or whether he or she is married or single. The difficulty is that, for a number of reasons, it is not at all reliable and its use can bring with it significant dangers.

Profiling Principles

Dr Canter appears now to be focusing more on the issue of geographic (where the suspect is likely to live or work) rather than psychological profiling. The few that I can find from the literature appear to be as follows.


This principle is more successful when considering a series of rapes/murders which occur in clusters in bigger towns and cities, as it lies in developing a relationship between the location of the crimes and where the criminal lives (or sometimes works).

Commuters live outside the area of the crimes and focus their offending in one or two specific areas where they feel comfortable, perhaps because they have lived or worked there at some time, or believe that it is where they are more likely to find the type of victim they seek.

Marauders live in the area where the offences occur. The problem for the detective is that until he or she catches the criminal, it is unclear whether they are a commuter or a marauder, as this factor is not predictably associated with any other, for example if the marauder always attacked their victim in a public area it would be possible to associate these two factors. All the investigator has are clusters of similar crimes probably committed by the same person who feels comfortable working in that area — and he or she knows that already.

Three Types of Rapist/Murderer

Dr Canter describes three different types of rapists according to how they treat the victim: as an object, as a victim or as a person. He believes that this can be useful as each has distinctive features which may assist the investigator to identify potential suspects.

The victim as an object. Here the rapist is only interested in the victim as something to control. He has no feelings towards them, not even anger, and only uses them to fulfil his inner fantasies.

Features of this type of offender are:

    • the assault is made in public and the victim is usually a target of opportunity
  • he will tend to attack the same type of person – young girls, older women, gay men
  • the control may continue after death – necrophilia, retention of the body or body parts, cannibalism • he is unlikely to be living with a partner.

The victim as vehicle. This person has much in common with the first. The key difference is that he sees the role that empathy can play although he has never or rarely felt it for anyone, certainly not his victim. She is seen as someone to be exploited so that the killer can somehow restore himself to being the person in control.

Features of this type are:

  • he may have a history of unsuccessful relationships
  • the initial contact may not be threatening to the victim
  • the location may carry some meaning for the attacker
  • emotional events in the killer’s life may provide the trigger for the assaults to begin or temporarily stop
  • he will tend to be a commuter
  • he will be from the older end of the attacker age range, i.e. late twenties or early thirties.

The victim as a person. This attacker come as close to ‘normal’ as is possible in that he tries to empathize with the victim and succeeds in his own distorted ay. During the course of the assault he will attempt to develop a relationship with the victim, perhaps by asking about boyfriends and other personal details. In this way he confuses the rape with a real sexual relationship. Features of this type are:

  • he moves to rape from other crime, especially burglary
  • he may stalk the victim first
  • he may break into the victim’s house and wait for her to return
  • he may be living with a partner although it is probable that the relationship will be a difficult or uneasy one in which he continually seeks to dominate.

Other Descriptive Factors of Serial Killers

The literature describes the following factors as being common to serial killers. It does not give any dues about how many of the seven factors you are likely to find, or the likelihood of any particular one being present.

Serial killers tend to:

  • be working-class, in unskilled jobs providing a low income and little job satisfaction
  • come from families that were dysfunctional in serious ways – rejection by one or both parents is a feature • be poor at forming relationships
  • be the runts of the family, small in stature
  • have been poor achievers at school
  • have become involved in minor crime at an early age • have ‘psychopathic’ personalities (whatever that may mean – my psychopath may be your sane but obsessed collector).

Crime Fiction Writing Task

Draw a diagram of a scene of crime. Using only five pieces of evidence, write a scene from a crime novel, showing the investigative methods of your detective as he visits the scene.

Kelvin I Jones is the author of the John Bottrell crime series, featuring a Cornish detective, many books about Sherlock Holmes and a biography of Conan Doyle. He has published the definitive guide to Cornish Witchcraft and several books about Cornish folklore. He is also the author of many supernatural stories, among them Carter’s Occult Casebook, about a psychic Edwardian detective. Of his many gothic tales, Francis King, the novelist and critic, has written, “(Kelvin’s work) piquantly suggest the work of a modern M.R. James.”

His new collection of crime short stories, Inspector Ketch of Norwich is on Kindle and will be available in paperback from 1st September via Amazon.

See the rest of Kelvin’s Blog post on how to write crime fiction here.

Kelvin Jones

Kelvin I. Jones has been a prolific UK crime and supernatural fantasy writer for over a quarter of a century. Born in Kent in 1948, he is equally at home writing poetry, plays and novels. He has published six books about Sherlock Holmes and the only definitive study of Conan Doyle’s interest in spiritualism, as well as numerous articles about the Victorian detective (see R De Waal’s Universal Sherlock Holmes, online edition, 2000). Ed Hoch, the renowned American crime writer, has said of his Sherlockian work: “Kelvin I Jones reveals a sensibility and knowledge of 19th Century literature that extends far beyond the world of Sherlock Holmes.’ He is the author of the Stone Dead series, featuring the intrepid Cornish detective, John Bottrell, and the Inspector Ketch stories, which are set in Norfolk.

Recent publications: Sherlock Holmes: The Plagues of London, Sherlock Holmes: The Baskerville Papers, A Dogged Detective (DCI Ketch), A Grave For The Goddess (John Bottrell).



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