A is for Arsenic (34 page)

Agatha and ricin

In
The House of Lurking Death
, Tommy and Tuppence's investigation into an attempted arsenic poisoning case quickly
escalates into finding a mass-murderer. The morning after Lois Hargreaves had engaged the detective duo, Tommy reads in the paper of a fatal case of poisoning at her home, Thurnley Grange. Miss Hargreaves died less than 24 hours after voicing her concerns about being poisoned. There was a second fatality, a parlour maid called Esther Quant, and two other members of the household, Dennis Radclyffe, Miss Hargreaves's cousin, and Miss Logan, a distant relative of Dennis, were seriously ill. Tommy and Tuppence hurry down to Thurnley Grange to find out what is going on.

By the time Tommy and Tuppence arrive at the house Dennis Radclyffe has also succumbed to the effects of the poison, but Miss Logan is still clinging to life. The source of the illness seems to be a plate of fig-paste sandwiches served at tea the previous afternoon. The cause is initially thought to be ptomaine (or food) poisoning, of a particularly virulent kind. The typical symptoms of food poisoning, vomiting, diarrhoea and stomach pain, would also be displayed by victims of ricin poisoning. Because of the earlier attempt on Miss Hargreaves's life, the doctor who treats the victims, Dr Burton, is suspicious of foul play, and the fig paste is sent for analysis. While they wait for the results to come back, Tommy speculates with Dr Burton about arsenic being added to the fig paste, because this poison had been added to chocolates in the earlier murder attempt. Dr Burton dismisses this theory as arsenic would not have killed so quickly. His initial theory is that a powerful vegetable-based toxin has been used.

Whatever the poison was, it killed its victims within 12 hours. Tea would have been served at around four o' clock in the afternoon, and both Lois Hargreaves and Esther Quant must have died during the night before the newspaper deadline, otherwise Tommy and Tuppence couldn't have read about it in the morning paper. Twelve hours is unusually quick for ricin, which normally takes three to five agonising days before the victim finally succumbs. Perhaps the murderer added a particularly high dose to the fig-paste sandwiches? Ricin, which does not have a particularly strong flavour even in a
very large dose, would probably be masked by the flavour of the figs.

Later, the doctor sends a note to Tommy and Tuppence, saying that he has ‘reason to believe that the poison employed was ricin'. There are no details telling us what these reasons might have been, and no description of any test having been carried out, but then in 1929 there
was
no test for ricin. The victims at Thurnley Grange had inflamed gastrointestinal tracts, and exhibited haemorrhaging; it was probably these symptoms that indicated ricin. There had been no cases of murder by ricin poisoning in Britain at the time Agatha Christie was writing this book, but there would have been cases of accidental ingestion of the seeds, and the symptoms and signs at post-mortem would have been known from these cases. Without a specific test being available, however, the best that could be done to confirm ricin as the poison would have been to inject an animal with ricin, or to add it to the animal's feed, and then compare the symptoms and post-mortem characteristics. This would take considerably longer than Christie allows for in
The House of Lurking Death
.

As if to confirm the suspicions of ricin, Tuppence remembers seeing some castor oil plants in the garden at Thurnley Grange. A book is also found in the house,
Materia Medica
, a work that collects together information about substances with therapeutic properties. The book is found open on the page for ricin, and contains enough information to provide a method for extracting ricin from the seeds of the castor oil plant. This seems an unusual thing to include in a book intended for medical benefit, as ricin has never been used as a therapeutic agent. Castor oil has been used for thousands of years as an emetic, a laxative, and even as an anti-dandruff treatment, and details of how to extract castor oil would presumably include methods for ensuring ricin was
not
extracted along with the oil.

The third victim at Thurnley Grange, Dennis Radclyffe, presents Tommy and Tuppence with a problem as they try to crack the case, as he was not at home when the fig-paste
sandwiches were served. It is clear that Dennis had been poisoned with the same poison as the others; he was also taken ill the same night as the others, and by five o'clock in the morning he had also succumbed to the effects of poison. Dennis was spotted drinking a cocktail before dinner, and it was shortly after this that he complained of feeling ill. The glass was found and sent for analysis, which confirmed that ricin was present (although again, how this was achieved is not clear). Also, the time between ingestion and death is again unlikely, as symptoms of ricin poisoning would not have been expected to present themselves for about six hours after ingestion, with death occurring several days later.

Adding ricin to a cocktail is not the best way to poison someone; the high alcohol content in the drink would probably denature much of the ricin protein. Alcohol causes proteins to unfold. Their three-dimensional shape is changed considerably, so the protein is no longer able to carry out its function.
⁸⁹
A cocktail such as a traditional martini would have 30 to 40 per cent alcohol, which would be expected to denature a large proportion of any protein such as ricin. There would have to be a very large dose of ricin in Dennis's cocktail glass to ensure that enough protein survived the alcohol and digestive processes to be absorbed into the body and cause such a rapid death.

The next five paragraphs contain significant spoilers. If you do not want to know who did it, look away until page
here
(and if you wish to read
Partners in Crime
– and I hope you do – this crime is just one of the 14 mysteries that make up the book).

The fourth victim at Thurnley Grange, Miss Logan, who also ate the fig-paste sandwiches, was still ill but was expected
to make a good recovery. Victims of ricin poisoning who survive beyond five days are usually expected to recover, so it may have been a little premature to give Miss Logan such a positive prognosis after only 24 hours. More importantly, how did she manage to survive for so long when the other members of her family died within hours? Maybe she didn't eat as many sandwiches as the others. Or perhaps there was another reason, as Tuppence would discover.

When interviewing Miss Logan, Tuppence notices some marks on her arm that look like pin-pricks, or the marks of a hypodermic syringe. Thoughts of Miss Logan being a morphine or cocaine addict are quickly dismissed because ‘her eyes were all right'. So what was the cause of the marks? It turns out that Miss Logan had been deliberately injecting herself with small amounts of ricin.

Miss Logan's father was a pioneer of serum therapeutics, a vaccination that protects an individual from a particular disease or toxic substance (known collectively as antigens). Agatha Christie correctly states that ricin was used as a tool in the early days of research into immunology. Injections of small amounts of some toxic substances can be used to build up a natural immunity to larger, normally lethal doses. By introducing the immune system to non-lethal levels of a toxic protein, antibodies are developed and a ‘memory' formed of the toxin. The antibodies are very specific to the molecule they bind to, and a body will build up a library of antibodies in response to exposure to a wide range of antigens over the course of its lifetime. An antibody binds tightly to its antigen, preventing it from entering cells in the body; it then stimulates its removal by cells called macrophages, which engulf and destroy foreign bodies, and they also trigger further immune responses. Hypodermic injections of small amounts of ricin would enable the body's immune system to produce anti-ricin, so were a larger, normally lethal, dose to be given, the body could rapidly inactivate the ricin, and the person would survive.

The body's response to the presence of ricin can now be used for its detection in poisoning cases (a test that post-dates
Christie's writing of the book, of course). Ricin antibodies can be isolated and modified for use in laboratory tests called immunoassays. Anti-ricin can be radiolabelled (tagged with radioactive particles), or modified to emit light when ricin binds to it, indicating that ricin is present in a sample. Many such antibodies have been developed, binding to various d
rug m
olecules and allowing the rapid screening of sa
mples for mu
ltiple compounds. Other techniques, such as chromatography, can be used to identify other compounds that occur in castor oil plants, and these can be used as proxy markers for ricin exposure. The incredibly small quantities involved in ricin poisoning continue to challenge the limits of detection, though, and there is still no standard, approved method for detecting ricin, either in the environment or in human tissue.

In
The House of Lurking Death
, Miss Logan must have started her preparations for murdering her relatives weeks or even months before adding poison to the fig-paste sandwiches. Extraction of ricin from the castor oil plants in the garden could have been carried out at almost any time, as ricin can easily be stored and stockpiled for the right occasion. Miss Logan then injected herself regularly with tiny amounts of ricin, to give herself immunity. One day she added ricin to the fig-paste sandwiches served at tea, and was able to eat some, safe in the knowledge that, although she might be ill and therefore unlikely to be suspected, she would not die. Later in the evening, she followed up by adding ricin to Dennis's cocktail glass. Esther the parlour maid was not an intentional victim. She simply made the mistake of eating a sandwich on the sly – with death her ultimate punishment.

Notes

⁸⁵
This is due to an enzyme in the cell, protein disulfide isomerase. The body has to split up disulfide binds regularly in the course of its normal function, so it is not surprising that there's an enzyme to do this.

⁸⁶
Appropriately.

⁸⁷
The two protein chains that constitute ricin occur in many other plants, but not together. Plants that contain only chain A, barley for example, are safe to eat even though they contain the poisonous half of the ricin protein, because without chain B, chain A cannot get inside the cells to do any damage.

⁸⁸
The pretty mottled beans are sometimes picked and eaten by children, who obviously don't know about their deadly properties. Apparently they taste like hazelnuts; I don't recommend finding out for yourself.

⁸⁹
This is why alcohol gels are used to sanitise hands. At concentrations of 70 per cent, alcohol can be absorbed through the cell membranes of bacteria, denaturing the proteins inside and killing the organism.

The Mysterious Affair at Styles

A final convulsion lifted her from the bed, until she appeared to rest upon her head and her heels, with her body arched in an extraordinary manner.

Agatha Christie,
The Mysterious Affair at Styles

THE Mysterious Affair at Styles
was Agatha Christie's first novel, and it contains all the ingredients for her classic style of detective fiction. We have a lethal poison, a brilliant detective, a bumbling assistant, a police inspector getting everything wrong, and all in a lovely country house setting; there is even a false beard to try to throw us off the scent. This is the book that introduced the world to Hercule Poirot, and saw the dramatic demise of Mrs Emily Inglethorp in a sinister case of strychnine poisoning. With only one victim you might think this a straightforward case but there are plenty of suspects, from the gold-digging younger husband to inheritance-hungry offspring
and vengeful staff – we are spoilt for choice of motive and opportunity. Among the suspects is a world expert in toxicology, a nurse, a doctor and a young woman working in a hospital dispensary. Only one thing seems certain: that the victim was dispatched with strychnine – but the real mystery is how, and by whom. Poirot guides us through a staggering array of red herrings and false leads, helped and hindered by the faithful Captain Hastings.