If you see a term that’s bold it’s defined in the Glossary. Only the first time that the word appears in the chapter will it be indicated in this way.

Poisons have been woven into romances, mysteries and stories for many centuries. Edgar Allan Poe is credited with writing the first fictional detective story (The Murders in the Rue Morgue) in 1842, which was followed quickly by series featuring Sherlock Holmes (1900) and Hercule Poirot (1920).¹  Poisonings became favourite plot devices of murder mystery writers,^2–4  with certain culprits like arsenic and strychnine (Chapter 8) making cameos again and again.

However, the limited scientific knowledge of some writers meant that sometimes poisons were either imaginary or not named. Even if poisons were named, the effects were often as fabulous as the story,⁵  and bore little resemblance to reality. As we will see later in this book, we can guess the identity of some poisons based on the effects and what the prevailing knowledge was at the time the story was written. However, sometimes the effects are so dramatic and quick that working out the chemical culprit is something of a challenge. Another favourite writers’ trick was to kill off characters with an unrealistic dose – the merest whiff from a chemical bottle, a pinch of powder, or single leaf of a poisonous plant (see Chapter 7). Of course, even if the writer had a good knowledge of the poison they were using, if it was left to actors to perform a play or opera they would usually go for an ostentatious death on stage (after delivering several final speeches⁵ ) with whatever symptoms had the most dramatic potential. We will see that some poisons act slowly and over a long period (meaning death could take months⁶ ) whereas others are fast-acting and really can cause death within minutes.

Then there was the hair-raising fictional identification of poisons at the scene by doctors or policemen, by sniffing, licking or rubbing suspicious samples on the lips (none of which are recommended techniques used today). Of course there are a few poisons that can be detected by smell, such as cyanide, with its characteristic bitter almond odour, but as we will see in Chapter 10, not everyone can smell it.⁵  Before the 19th Century poisons were often declared ‘untraceable’,⁴  but later detective novels introduced more science to the scene of poisonings,⁷  with the development of forensic science.⁸  This also coincided with more chemical poisons becoming available as household items. They started lurking in the kitchen, the medicine cabinet and the shed.⁹  Before this, most poisons available to murderers or suicidal characters came from plants or animals.¹⁰ 

You might think from reading fiction that all poisonings are fatal, and indeed in Ancient times there were few or no treatments for poisoning,⁹  so this was the usual outcome. But we now have antidotes to many poisons, some treating the symptoms and some working specifically against the chemical, such as naloxone, which reverses heroin overdose. In Chapter 6 we will meet the antidote to digitalis poisoning, and see how, somewhat unrealistically, James Bond manages to ‘recover’ and get back to his martini without it. Some antidotes are themselves hazardous, and doctors can end up fighting one poison with another.¹¹ 

In fiction, the author often shows the reader the poisoner devising and enacting their sinister schemes (there is a good example of this in The Count of Monte Cristo in Chapter 8), but in real life, poisoners are rarely seen in action. They are usually caught through circumstantial evidence, such as buying something poisonous, or because they confess. The plots of fiction can also suggest a complex web of motives and connections between poisoner and victim, but actual motives are the same as for other killings – money, power, love, secrecy, jealousy and revenge. As in real life, poisonings are used in fiction to remove political opponents (even if they are a family member like in Hamlet (1600), see Chapter 3), or to dispatch an unwanted partner or a step-child who stands to inherit a fortune (see Chapter 8).¹²  The calculated intelligence needed for a murder by poison makes for a good plot line,¹³  but the modern-day fatal poisonings investigated by forensic toxicologists are much more likely to be accidents or suicides. Accidents are usually avoided by writers (unless as part of a vague backstory), but there are a few examples of suicides in the literature, such as the death of Shakespeare’s Romeo (see Chapter 5).

In each of the chapters we will look at a different poisoning case study. Each involves a different chemical and a different manner of death (suicide, accident, murder, death in custody, etc.). In some case studies we know the name of the poison, such as oleander in Chapter 7, but in others we will need to use forensic toxicology to identify it. The first section of the chapter will look at the investigation of the scene, including the symptoms the victim experienced, where the poison could have come from, and who might attend the scene if it happened in modern times.

In some cases, such as The Jew of Malta (1589) in Chapter 2, people were declared ‘dead’ incorrectly. Devices that can detect faint heart signals and activity within the brain are modern inventions,¹⁴  and when this play was written, appearing not to be breathing or looking blue were usually enough ‘evidence’ to pronounce someone dead. Although Coroners were established in England in 1194, not all suspicious deaths were subject to the rigorous investigation they are today. Mortality rates from disease and natural causes were so high that many deaths (particularly those of poor people) would have been accepted at face value as ‘natural’. Some poisoning symptoms also looked very like diseases such as cholera.¹²  Perhaps deaths of the more wealthy might have involved an “inquest”, but with no way of testing for poison in the body until the late 19th Century, there was a good chance you would get away with murder.¹⁴  Before science was routinely used, diagnosis of poisoning relied on the symptoms being witnessed and the obvious presence of poison in the stomach contents (such as plant material) so it was not particularly reliable.¹⁵  Even today, poison rarely leaves external marks on its victims (with the exception of snake bites), but there are certain clues at the autopsy that can point to a poisoning.

The second section of each chapter looks at the poisons themselves. Sometimes we know what the poison was, and in other cases we will use the symptoms to suggest the culprit. As we have seen, plants were the main source of medicines and poisons until the 19th Century. The same plant can be both medicinal (a useful herb) and toxic (a dreadful poison), it all depends on the dose. This made them good plot tools, because many of these plants, like poppies (Chapter 2), aconite (Chapter 5), henbane, hemlock and yew (Chapter 3) grow wild or were cultivated in people’s gardens for ‘medicinal’ reasons.¹²  This allowed authors to cast the net wide for the culprit.

Of course, some gardens had more poisons in them than others; as we will see in Chapter 4, religious orders such as monasteries and convents had medicinal herb or ‘physic’ gardens. This medical legacy was probably left by the Romans and maintained by the Christian church. In medieval times, knowledge of plants was often kept within these orders,¹⁴  and it was common practice to give combinations of herbs in certain ways for religious purposes, and to treat those in pain.¹¹  Outside of the state religion there were Druids and ‘wise women’,¹⁴  but during the 15–17th Centuries they were accused of being pagans or witches.¹⁶  This risk of persecution made collecting herbal ingredients a risky business,¹¹  and this is where much of the folklore surrounding them has come from.¹⁷  Instructions such as picking herbs by moonlight were probably less to do with potency (thought then to be related to the power of the moon¹⁸ ) and more to do with not being seen. Nevertheless, some knowledge was passed down between generations of women, and we see an example in fiction of a successful folk remedy using digoxin from a female healer in the 19th Century (Silas Marner) in Chapter 6. Other folklore sprang up to keep people (especially children) away from dangerous and valuable plants, and we see some of the weird and wonderful myths about mandrakes in Chapter 2.

Indigenous healers and herbalists also (still) prescribe herbs for various symptoms, e.g., in Traditional Chinese Medicine (TCM), Kampo (from Japan) and Ayuverdic medicine (from India). A high percentage of the World’s population still relies on these herbal medicines, as modern Western healthcare is too expensive, mistrusted, or not available to them. Many of the remedies still in use today can help people, but others are at best innocuous and at worst toxic,¹⁹  as we will see in some of the modern toxicology cases we will explore later in the book. The rise of the internet has meant that herbal medicines are easier than ever to buy, and consumers are often led to believe that ‘natural’ is the same as ‘harmless’.²⁰ 

In the UK over time, knowledge of plants spread to the reading public as herbalists began to publish accounts of plants and their medicinal properties, known as “herbals” (the first one being published in English in the 1520s).²¹  These books were designed to help people correctly identify plants and prepare and use them as medicines. Famous examples of herbal authors include John Gerard,²²  Nicholas Culpeper, Richard Banckes,²³  and William Turner.²⁴  Turner’s was the first to be published in English (not Latin) setting a precedent for later herbalists.⁹  In Turner’s birthplace in Morpeth, Northumberland there is a free public medicinal garden devoted to the plants he included in his book (Figure 1.1). Some other medicinal and poison gardens have survived, such as the Chelsea Physic Garden in London, The Poison Garden in Alnwick, and The Oxford Botanic Garden and Arboretum, but these others now have entry fees.

The introduction of new printing technologies in Europe saw herbals become more widely available, and by the 16th Century, pharmacies or apothecaries (see Chapter 4) began to emerge. For writers during this period such as Shakespeare, Jonson, Marlowe and Webster, herbals would have been their main source of inspiration when choosing poisons for their plots.^25,26 

The writers of herbals during the 16th Century copied extensively from earlier Roman and Greek authors such as Dioscorides, taking their knowledge at face value.⁹  Unfortunately much of what was in these early herbals was incorrect and dangerous, and reputations for ‘cures’ probably emerged when people got better by chance after being given an ineffective herbal remedy. Placebo effects also played an important role.²⁷  Conversely, the dangerous effects of some toxic herbal treatments were likely missed when the patient died, apparently of their original ailment.

Herbals usually suggested ingesting medicinal and poisonous plants by making some kind of drink (tincture or decoction) out of the leaves, but some plants contain useful or deadly chemicals in their roots (e.g., mandrakes in Chapter 2), seeds (e.g., strychnine in Chapter 8) or fruits (e.g., deadly nightshade in Chapter 4).²⁸  Ingestion remains the most common way to take in poisonous plants, but some can also cause skin irritation when touched, give off toxic fumes or be smoked. The chemicals in these plants are known as “alkaloids” and contain nitrogen.²⁹  They are designed to be a source of nitrogen for the plant (for growth and propagation²⁹ )³⁰  and defend them from herbivores, so are often exceptionally bitter.³¹  This means the berries of poisonous plants often have a sharp taste, leading you to spit them out,⁹  although deadly nightshade berries are dangerously sweet-tasting and look a bit like blackcurrants (Figure 1.2). When used for murder, plant poisons therefore need to be disguised in strong-tasting foods such as curries.³² 

The mouth, throat and stomach are usually the first parts of the body to be affected when poisonous plants are ingested. When the rest of the digestive system comes into contact with the plant this leads to nausea, abdominal pain, vomiting and diarrhoea. This is the body attempting to expel the poison before it gets any further, but if the poison passes into the liver it is usually broken down and eliminated.³³  Some poisons produce tingling or burning sensations, or more serious spasms and convulsions as they target our nerves. Normally impulses travel along nerve fibres as tiny electrical currents,³⁴  but some poisons can intercept these causing the electrical signals to falter,¹³  or as in the case of strychnine, overexcite the nerves.

Another way to kill a victim with nature was using a venomous animal, such as in Cleopatra (see Chapter 9). Venoms are injected directly into the blood by fangs or stings, and can affect the skin, heart and cells in ways that range from minor to fatal.³⁵  Unlike the alkaloids that plants use to defend themselves, venoms are used to attack and stun prey.^30,36  Some of the herbals mentioned above contained antidotes for venomous bites made from plants,³⁷  but as we will see in Chapter 9, these do not work and can waste valuable time before seeking effective medical treatment.

In the third section of each chapter we will explore other works of fiction employing the same poison; these sources can be novels, plays, films, operas or even computer games and graphic novels. Sometimes the poison is used to kill or injure a victim, in other cases it is mentioned figuratively, such as in The Man Who Laughs by Victor Hugo. Poisons have been popular plot devices since Ancient times and crop up in sources as broad as Greek myths,³⁸  the Bible, spy novels and Harry Potter.

Where we know or can guess the chemical culprit, we will examine how realistically the author has portrayed the dose, the symptoms and the way in which the poison was delivered. Most are delivered by mouth, but there are some unusual routes such as via the ear in Hamlet, or by touching, wearing or kissing poisoned objects such as robes, skulls, helmets and paintings (e.g., The White Devil by John Webster). Most plant poisons absorb poorly through the skin, although some can cause a local reaction (such as aconite, Chapter 5), but others like arsenic, strychnine, and several modern herbicides could cause a more extreme skin reaction or even death.³⁹ 

The association between poisons and the supernatural is long, with lots of plants having supposedly magical powers, links to the Devil or the ability to conjure up creatures such as fairies (see Chapter 6).¹²  Sickness itself was often put down to supernatural forces entering the body, so any cure should be likewise.⁴⁰  This was because before germs were understood, the seemingly random nature of disease could only be explained by the supernatural.⁴¹  In this belief system, plants could protect the soul as well as the body from harm, and their divine magic required certain rituals to ensure their potency.²⁷ 

As medical knowledge developed and the causes of sickness were found to be more earthly than divine, the magical properties of plants became old wives’ tales that were passed down orally from one generation to another to keep people (especially children) away from danger.¹⁸  Other tales come from recipes for flying ointments and magic potions that included so-called “hexing herbs” such as henbane (Chapter 3). The dual nature of many plants (healing and harming) increased the mystery around them, giving them a supposedly protective role when worn as amulets or charms.¹⁸  Some plants such as aconite (Chapter 5) are associated with particular gods, and others bring on hallucinations, allowing the user to communicate with the divine.⁴²  Other myths sprung up about harvesting plants during particular phases of the moon, likely linked to the gods being absent at particular times.¹⁸ 

A surprising number of deadly poisons also have medicinal uses, if the dose is right. One of the difficulties in using herbal remedies is that the potency of the plant depends on the growing conditions and the plant’s age and the season. Modern medicine therefore uses the pure alkaloid, sometimes made in a lab and sometimes extracted from the plant. In these sections we will look at what good (if any) the poison can do. You may know that morphine from opium poppies (Chapter 2) is a common pain-reliever for example, but maybe not that the alkaloids from yew trees are useful chemotherapy agents (Chapter 3), or that chemicals from snake venoms can promote blood clotting (Chapter 9).

Plant material is still used as medicine in TCM and homeopathy, but European regulations for licensing and selling herbal products as medicines (rather than as ‘supplements’) have limited their widespread use.²⁷ 

In this part of each chapter we look at some of the modern cases forensic toxicologists have encountered with each poison from all over the World. As we have seen, poisonings are not always fatal, and the real-life cases we will explore range from minor symptoms to hospitalisation and death. The victims range from the very young to the very old, and the circumstances also vary, with many accidents (e.g., where poisonous plants were mistaken for something edible), workplace poisonings, suicides and some homicides. The many advances in detecting drugs and poisons in the body since the 19th Century⁴³  mean that thankfully today’s poisoners are very unlikely to get away with it. Not all ‘classic’ poisons are seen in modern forensic toxicology labs; arsenic, which was once a very popular poison (being easy to dissolve with no taste or smell³⁸ ), is rarely seen nowadays and so does not feature in this book. Its decline from its heyday is probably due to tighter legal restrictions on its sale and the early development of tests for it in the body. This book also does not feature ‘celebrity’ or high-profile real-life poisonings. There are excellent books that already give the details of these classic cases,^44,45  whereas this book focusses on the unnoticed and perhaps less glamorous day-to-day caseload of forensic toxicologists. Spy poisonings with cyanide may feature heavily in fiction, but in real life, cyanide is most likely to be found in victims of smoke inhalation during a domestic fire (see Chapter 10).

Forensic toxicology cases follow a complex lifetime; from the scene of the poisoning, to the autopsy where the body fluid samples are taken, the initial decision about what to test for, the clean-up of what can be very dirty samples, how we identify the poison, and finally how we make sense of what the results mean. In each chapter we will explore an aspect of a forensic toxicology case, explaining the pitfalls and challenges at each point to give a sense to the reader of how these cases are handled in real life.

In the penultimate section of each chapter we will look at how each specific poison might be found using the myriad ways they can now be detected in body fluids. You might be surprised to find that there is no standard set of tests for a forensic toxicology case. The decisions on what to test for are usually left up to the lab or the person submitting the samples for testing (the police or Pathologist). There are also no requirements for labs to use specific methods,⁴⁶  although some professional bodies have drawn up “best practice guidelines”.⁴⁷  Not all labs can afford the top-of-the-range equipment or the staff to operate it, so this has led to a lot of variation in testing throughout the World.

Although many of the case studies from fiction in this book focus on plant poisonings, most modern cases of poisoning typically involve prescription or recreational drugs, so these will be targeted by the lab.⁴⁸  There are also differences between hospital toxicology testing and forensic toxicology testing. In hospitals, rapid drug testing of urine for a limited set of drugs (see Chapter 11) based on immunoassays (see Chapter 6) is used to make quick treatment decisions,⁴⁹  and can sometimes be falsely negative.

In the final section of the chapter we will return to the case study and apply what we have learned about the poison(s) to the fictional poisoning. When passed through a modern forensic toxicology filter,⁵⁰  some are found to be unlikely or unrealistic, whereas other authors do a much better job of portraying a poisoning. Of course that doesn’t mean we can’t still enjoy our fiction, which is there to entertain us, but real poisoning cases often lack the finesse and romance of their fictional counterparts.³⁸