A is for Arsenic (40 page)

A chance observation reveals the clue to solving the case. Easterbrook sees the vicar's wife treating her dog for ringworm, rubbing some cream on the affected area to make the fur fall out; hair falling out is the only common symptom in all the deaths associated with the Pale Horse organisation. By lucky chance, Easterbrook had read an article about a case of industrial thallium poisoning in the United States. A lot of workers in a factory died one after another, but their deaths were attributed to a range of natural causes – paratyphoid (similar to typhoid but caused by different bacteria), apoplexy, alcoholic neuritis, bulbar paralysis (paralysis of tongue and muscles controlling the vocal cords), epilepsy and gastro-enteritis. The industrial case described in the novel was invented but it is similar to incidents
in the Netherlands in the 1930s. Christie, through Easterbrook, also discusses a thallium-based murder case (again in the United States) to highlight the wide range of symptoms thallium poisoning can present. The case was probably invented, but there was a spate of thallium poisonings in Australia in the 1950s that Christie could have drawn upon.

Mark Easterbrook alerts doctors and the police, and thallium poisoning is confirmed. There was no standard test for thallium in a murder investigation in 1961 as there had never been a recorded case of thallium being used for this purpose in Britain. Thallium was so poorly understood at the time that the causes of death would not have appeared suspicious, and even if a pattern had been detected, almost certainly the authorities would not have suspected thallium of being the cause. While the victim is still alive urine can be analysed to detect thallium, using flame spectroscopy. Thallium levels would have to be above a certain level to confirm a poisoning case, though, as it is such a common element that everyone has trace amounts in their bodies. Luckily these traces of thallium never naturally build up to dangerous levels.

Pointing the finger at thallium grows a little more difficult at a post-mortem. Aside from the loss of hair, there are few common symptoms that can be relied on. Internally there are no characteristic signs in the body to show the presence of this metal, and the damage caused by thallium can easily be attributed to natural diseases. Analysis of body tissue to prove the presence of thallium can also be very difficult. Thallium distributes itself so well throughout the body that only tiny amounts may be found in any particular organ. As analytical techniques have improved, the detection of smaller and smaller amounts of thallium has become possible.
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The method used to murder so many people in
The Pale Horse
is frighteningly easy, and it is a surprise that there had been no real-life cases in Britain before the book's publication. In the book, the Pale Horse organisation is an agency for contract killings. Someone with designs on advancing an inheritance or disposing of a despicable relative would contact an agent, who would take the details of the victim. A trip to the Pale Horse Inn in Much Deeping would see a sham seance, designed to give the impression of supernatural forces at work. Meanwhile the victim would be asked to take part in a customer survey on the types and brands of household products they used; later, they would receive another visitor posing as a gas-man, or an inspector from the electricity company. The visitor substitutes one household product for another, identical in appearance, but laced with thallium salts; it could be a type of tea, a cosmetic, a medicine, a soap or even a shampoo. The victim wouldn't even have to receive a fatal dose in one go, as the cumulative effects of regular doses of thallium would eventually lead to the same end result: a slow and agonising death.

Notes

⁹⁶
There are two ions of thallium, Tl
+
and Tl3
+
. Tl
+
is the most common, resembling the ions of the alkali metals in group 1 of the periodic table in its chemistry, and potassium (K
+
) in particular. Tl
+
will form strong chemical bonds to negatively charged atoms or groups of atoms to form a salt, such as thallium chloride (TlCl).

⁹⁷
These were used in several attempted suicides. Thankfully most people only swallowed one tube, which was not quite enough to kill, but it would have made them very ill.

⁹⁸
Some might be retained, but not enough to determine exposure to the metal reliably – this again is due to thallium's weak bonding to sulfhydryl groups.

⁹⁹
As we saw earlier, thallium has even been identified in the cremated ashes of murder victims, such as Bob Egle in the Young case.

Lord Edgware Dies

To die, to sleep,

To sleep, perchance to Dream; ay, there's the rub;

For in that sleep of death, what dreams may come,

When we have shuffled off this mortal coil,

Must give us pause.

William Shakespeare,
Hamlet

THE use of barbiturates as poisons dates Agatha Christie's writing as much as the clothes and cars described in her work. Barbiturates enjoyed a brief and notorious period in the limelight, between around 1920 and 1970. Initially they were considered a safe and effective sedative, but by the 1960s their dangers had been recognised and barbiturate drugs were slowly phased out of regular use as safer alternatives became available. Veronal was the trade name for the first barbiturate drug, released onto the market in the early 1900s. As the doctor in
Lord Edgware Dies
points out, ‘Veronal's uncertain stuff. You can take a devil of a lot and it won't kill you, and you can take very little and off you go. It's a dangerous drug for that reason.'

Christie described the use of barbiturates in several of her stories but employed them only four times for murder; two of her characters used barbiturates to commit suicide, an appropriate choice given that barbiturate overdose was a common way of taking one's own life at the time she was writing.

The 1933 Christie novel
Lord Edgware Dies
gives a most detailed description of the use of Veronal. The story centres around the death of the title character, who is found stabbed. The last person to visit Lord Edgware was his estranged wife, Jane Wilkinson, an American actress and rising star. The next day the papers report the discovery of Lord Edgware's body. They also say that Jane Wilkinson had attended a prominent dinner party the previous evening, giving her a seemingly unbreakable alibi.

The American title for the book,
Thirteen at Dinner
, refers to the superstition that if there are 13 people sitting at a dinner table, the first to rise will die. The dinner party where Wilkinson was seen had 13 guests, and she was apparently the first to rise. Luck seems to have been on her side, though, as it is another actress, Carlotta Adams, a young American actress and brilliant impersonator, who is subsequently found dead. Carlotta's character was based on the American actress Ruth Draper, famous for her character-driven monologues, but the character's death has many similarities to that of another real-life actress, Billie Carleton.

The story of Billie Carleton has some parallels with
Lord Edgware Dies
, and it certainly inspired the Agatha Christie short story
The Affair of the Victory Ball
. Billie Carleton was a young actress and singer who, in 1918, died in what was perhaps the first showbiz sex and drugs scandal. She attended a ‘Victory Ball' at the Royal Albert Hall in London, one night in
November 1918. The party continued at Carleton's flat until the morning, but by 10 a.m. her guests had finally left, and she made a telephone call, the last conversation she ever had. At 11.30 a.m. Carleton's maid arrived to find her snoring. By 3.30 p.m. the snoring had stopped. A doctor was called, and he attempted to resuscitate her with an injection of brandy and strychnine. The attempt failed. Though cocaine overdose was the accepted verdict at the time, it has since been suggested that Carleton in fact died of the barbiturates she had been prescribed to cope with her cocaine ‘hangovers'.

In
Lord Edgware Dies,
Carlotta's death is attributed to an overdose of the barbiturate Veronal. It is initially thought to have been an accident because a jewelled box of Veronal powder found in Carlotta's bag suggests that she was a regular user and, on this occasion, had taken too much. With one murder, one accidental death and an actress who appears to have been in two places at the same time, it's a puzzle that requires the genius of a legendary Belgian detective to solve it.

The story of barbiturates

Barbiturates are derivatives of barbituric acid, a compound first prepared by Adolf von Baeyer (1794–1885) in 1864. There are two stories that supposedly explain the naming of the acid. One has it that Baeyer was obsessed with a woman named Barbara, and he named it after her; the other holds that Baeyer made his discovery on St Barbara's Day. By 1900, around 2,000 variations on the basic barbituric acid unit had been created and tested; some of these were found to have beneficial effects on humans. These compounds form when barbituric acid is ‘cyclised', to form a ring structure made of two nitrogen atoms and four carbons. This basic structure can be modified by changing the groups attached to one of the four carbon atoms or the two nitrogen atoms. A bewildering number of variations is possible.

From the creation of the first barbiturates in the early 1900s, more and more were synthesised and released onto the market. They soon became the standard treatment for depression and insomnia.

Changes in structure can change the solubility of a compound in water and fats, and thereby change how readily the drug is absorbed into the bloodstream, as well as how easily it can cross the blood-brain barrier. A change in structure will also affect the strength of its binding to target sites in the nervous system, meaning effects can take longer or shorter times to kick in. The rapidity with which these groups can be removed by the body and rendered inactive also leads to different periods of sedation. Until barbiturates were produced, the only sedative drugs available had been bromides (see page
here
). Bromides had a very unpleasant taste, and were only moderately effective. They also led to many more side effects than barbiturates.

Barbiturates are white powders that would have been sold as tablets or as loose powder to be dissolved in water. They had a slightly bitter taste, but the tablets could be swallowed quickly (and barbiturates could be injected, though this was rare). Barbiturates were sold under a variety of trade names, but the actual names of the drugs were more formulaic – in the United States the name usually ended in ‘al', while everywhere else barbiturates could be identified by a name ending in ‘one'. For example, barbital and barbitone are the same compound – and this was marketed in the United States under the name Veronal. Veronal was widely prescribed as a sleeping drug because in low doses it acted as a sedative, and at higher doses as a hypnotic to render the taker into a state something like sleep.
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