A is for Arsenic (36 page)

Cream was caught; it took only 12 minutes for the jury to reach a guilty verdict, and he was sentenced to hang at Newgate prison. There were whisperings that a man standing next to Cream on the scaffold heard his last words as the bolt was pulled from the trapdoor: ‘I am Jack the …'
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Agatha and strychnine

The Mysterious Affair at Styles
provides such an insight into the chemistry of strychnine that it is worth looking at this novel in some detail. In the early hours of the morning the Styles household rushes to the aid of the very unwell Mrs Inglethorp. As they burst into her bedroom, they witness the old lady in the throes of the most violent convulsions. The seizures rack her body with such force that she has managed to knock over a heavy bedside table. A second bout of convulsions forces her body to arch in such a way as to leave her resting on the back of her head and her heels, with her belly forced up towards the
ceiling. Unsuccessful attempts are made to administer brandy to the victim (though what they hope to achieve with this is unclear). With her last gasps of breath, Mrs Inglethorp cries out the name of her husband before collapsing back on the bed, dead. Resuscitation is attempted, but to no avail.

The signs of strychnine poisoning are characteristic, and even the rather obtuse Captain Hastings recognises the symptoms immediately. Christie uses strychnine to kill off a total of five characters in her books, and only once is death suspected as being caused by anything other than strychnine – in
Poirot Investigates
, where a death is attributed to tetanus. The convulsions can be similar; this is where the word ‘tetanic' comes from in describing the type of convulsions experienced by Mrs Inglethorp. ‘Grand mal' seizures of epilepsy patients can appear very similar to strychnine poisoning, but Mrs Inglethorp was not epileptic and this scenario is never considered.

The death of Mrs Inglethorp is clearly suspicious, and a post-mortem is ordered, with the results confirming poisoning by strychnine; some of the poison is found in her stomach, with more found in other body tissues. The total dose is estimated to have been just under a grain (approximately 65mg). This is a little low for a lethal dose, which is normally quoted as 100mg, but 65mg may well have been enough to dispatch an older female victim. Indeed, a dose as low as 36mg has proven fatal.

Rigor mortis
sets in quickly after strychnine poisoning, and this has been known to lock the corpse in the pose of its final convulsion. This does not occur in all cases, and very large doses of strychnine can cause a rapid death with no convulsions at all.
Rigor mortis
wears off in time and strychnine would leave no obvious sign of internal damage in the body, but being aware of the circumstances of the death, a pathologist or toxicologist would know to look for the poison in the stomach contents. Strychnine could be extracted from the body using the Stas method (see page
here
). Specific and reliable chemical tests for strychnine were well established by 1920, but before
this pathologists would have recognised the distinctively bitter taste of the poison. Any doubts could be assuaged by feeding the unknown poison to an animal and comparing the symptoms to an animal fed with strychnine.

Today the extraction and identification of poisons is much more straightforward, of course. A range of analytical techniques is available to confirm the presence and identity of a poison. The main limitation on modern methods is making sure the right tests are carried out for the appropriate poison; there are so many compounds that can prove fatal if taken in the right dose that toxicological screenings normally look only for the usual suspects. Though no longer specifically tested for, strychnine would be detected as part of a regular toxicological screening for alkaloids at post-mortem.

Strychnine's heyday as a murder weapon is long gone, thankfully, owing to tighter controls on its export and use. Strychnine is banned in Britain, though it appears to remain frighteningly easy to obtain dangerous quantities in the United States. Between 1949 and 1979 there was approximately one death a year in Britain from strychnine poisoning, and this was usually self-administered and obtained from stocks kept for agricultural purposes. Occasionally strychnine cases present themselves in hospitals even today, but this is often due to an overdose of hudar traditional Indian remedies, with the symptoms being twitching or convulsions that tend not to lead to death.

The cause of Mrs Inglethorp's death would have been easy to establish. What was much more difficult to figure out was
how
it was done. First the poisoner had to get hold of strychnine. Today the sale and use of strychnine are carefully controlled, but things were a little more relaxed in 1920. Hospital dispensaries would stock strychnine, as it was prescribed as a stimulant. Pharmacists would keep it for sale as a pesticide or for use in tonics. Although strychnine was known to be highly
toxic and the sale of it was restricted, this imposed few obstacles to the determined poisoner.

As is the case with many other poisonous substances, the purchaser had to be known to the chemist and have a valid reason for the purchase before the sale could proceed. Both the buyer and the seller would have to sign a poison register recording the amount and intended use of the poison, along with the name and address of the purchaser. At least the poison register gave some measure of traceability in theory, but some poisoners – rather unsportingly – have been known to use false names and disguise their handwriting.

Having strychnine in your house today would be suspicious, but it would not have been unusual back in 1920. In
The Mysterious Affair at Styles
a bottle of strychnine is found in the hospital dispensary, from where several suspects had the opportunity to steal some. Another bottle of strychnine is found in a drawer in the house. Strychnine is bought from the local pharmacist to poison a dog (with the poison register signed in accordance with the law), and finally, there is strychnine in Mrs Inglethorp's tonic, a bedside drink to pep her up. None of these is in itself suspicious but, as Poirot puts it, ‘… there is altogether too much strychnine about this case'.

Strychnine is unremarkable in appearance, and at a passing glance it's indistinguishable from salt or sugar. A closer inspection may reveal that the long crystals of strychnine are different from the small blocks of salt or sugar crystals. It would be fairly easy, then, to add some colourless crystals to food or drink without being suspected, so long as no one was paying too much attention. However, strychnine is one of the bitterest substances known, and can be detected in water in quantities as low as one part in 70,000. This means that the murderer would have to dilute a fatal dose (100mg) in seven litres of water to disguise the taste, so the victim would be likely to be alerted to its presence pretty quickly, or they would be suspicious that they were being made to drink so much. Either the flavour has to be disguised or concealed somehow to
prevent the victim from becoming suspicious, or the fatal dose has to be swallowed in one gulp. Four possibilities are examined in the novel: the evening meal; a cup of coffee taken just before bed; in cocoa kept in a warming pan by the bedside of the victim; or in one of the medicines taken by Mrs Inglethorp.

First, the evening meal. Mrs Inglethorp ate the same as everyone else, but she did not eat very much. To avoid the bitter taste a fatal dose of strychnine would have to be thinly distributed throughout the food, so it seems unlikely that the poison could have been administered this way. Also, the death occurred many hours after the meal was eaten, and it usually takes less than 30 minutes for the effects to manifest themselves. The onset of symptoms might be delayed slightly by a heavy meal, but that does not seem possible here.

Second, the cup of coffee. This would seem a very good contender, as the strong, bitter taste of the coffee could cover the taste of the strychnine. There is a difficulty, though, because the coffee was taken after the evening meal, and the symptoms did not present themselves until the early hours of the morning. Other drugs could have been added to delay the onset of symptoms, but more of this later. In the end the coffee is eliminated, as Poirot discovers a fresh coffee stain on the carpet where Mrs Inglethorp must have dropped the cup, so she never actually drank it.

Third, the cocoa. This can be dismissed almost immediately, as it would not be possible to disguise the bitter taste of strychnine, and it would be unlikely that anyone drinking a strychnine-laced cup of cocoa would take more than a sip. However, Poirot determines that there is another substance dissolved in the cocoa, a narcotic. The word ‘narcotic', from the Greek meaning ‘to make numb', can mean different things to different people, depending on whether you are a layperson, work in law enforcement or work in the medical profession. We are never told what the narcotic is or what Christie means by the term, but we can assume that she was probably referring to a morphine-like substance because of the effects it produces in the victim.

In addition to its well-known pain-relieving effects, morphine is very good at inducing sleep. It is unlikely that morphine would induce dramatic tetanic seizures so it was not a morphine overdose that did away with Mrs Inglethorp, but morphine
was
involved in her demise.

Morphine affects the digestive tract by impairing the muscle contractions that normally move food from the stomach to the small intestines and on through the many metres of gut. For years it was used as a treatment for diarrhoea for this very reason, and it is why many users of morphine-like drugs complain of constipation. This has the effect of delaying the movement of food from the stomach to the small intestines by as much as 12 hours. As we have seen, strychnine is not absorbed in the stomach owing to the acidic environment, but it is absorbed through the small intestine. This could explain the delayed effects of the strychnine dose taken by Mrs Inglethorp, several hours before the convulsions started.

Finally, we must look into Mrs Inglethorp's medicine cabinet. Here there are two possibilities: the sedative powders and the tonic. The small packets of sedative powders contained potassium bromide. Bromide powders could be purchased in boxes containing several individual doses from pharmacists. Each dose would be a few grams of white powder folded up in paper. The powder would be dissolved in water and swallowed. Potassium bromide was widely used as a sedative for epilepsy, as it calmed the seizures, and more extensively as a general sedative. It was commonly thought that bromide was added to soldiers' tea during the Second World War to reduce libido. This is unlikely to be true – bromide powders would also act as a sedative and reduce alertness, a distinctly undesirable side effect in an army at war.

Bromide powders are not completely innocuous, and with a high level of use can cause serious health problems. Bromide is retained in the body for a long time. The half-life for elimination is nine to twelve days, so it is relatively easy to ingest more than is being excreted if the powders are taken regularly over an extended period of time. Could bromide
poisoning, known as bromism, account for the symptoms displayed by Mrs Inglethorp on the fatal night?

People with bromism display a wide range of symptoms including lethargy, slurred speech, headaches and psychiatric effects such as depression and confusion. Seizures have been observed in some cases, but not of the type seen in strychnine poisoning, and death from bromism is rare. Any symptoms would have been present a long time before Mrs Inglethorp's death, so the bromide powders can be discounted. There is, of course, the possibility that the powders had been tampered with and strychnine added, but the last powder had been taken two days previously, so again they can be discounted.

Mrs Inglethorp also took a tonic every night. This was a pick-me-up or stimulant quite commonly used in the early part of the twentieth century; the principal ingredient was strychnine. It was believed to stimulate digestion and make you feel brighter and more alert. A most unusual example of its use occurred in 1904, when athlete Thomas Hicks won the marathon at the St Louis Olympics. During the gruelling race Hicks was given two doses of 1/60 grain (approximately 1mg) of strychnine and at least a flask of brandy by his trainers, in the belief that it would keep him going. He managed to finish but he had to be carried across the line, and was too weak to collect his medal. If Hicks's trainers had been any more helpful they could have killed him.

Research has debunked the claims that strychnine acts as a stimulant. Doubts over strychnine's efficacy started in the 1950s, and by 1972 it was completely discredited as a therapeutic agent. In 1920, though, small quantities would be diluted to ‘safe' levels and sold over the counter without prescription. Mrs Inglethorp would not be unusual in having a bottle of strychnine-based tonic on her bedside table. The only problem with the tonic as a source of the poison is that Mrs Inglethorp had swallowed the last dose on the night she died. Even taking several spoonfuls at once would not be fatal. If she had been taking the tonic previously with no ill effects then clearly there could not have been a mistake in making up the prescription.