A is for Arsenic (31 page)

How phosphorus kills

White phosphorus can burn the gullet and stomach as easily as it can burn the skin owing to its highly reactive nature. In large quantities it damages the stomach lining, causing haemorrhaging and intense pain, with vomiting of blood. The vomit may smoke as the phosphorus reacts with oxygen in the air, and there will be a garlicky smell. Phosphorus will also
react with stomach acid to produce phosphine gas (PH
3
), which has a particularly pungent smell that can be detected on the victim's breath. There would be a burning sensation in the mouth, and victims experience a strong thirst. Smaller quantities of phosphorus may inflame the stomach lining without causing vomiting, although a garlicky smell on the breath may still be detectable. Absorption from the gut into the bloodstream is relatively slow and can take between two and six hours, but this will be faster if the victim has eaten greasy or oily food. When the initial symptoms of pain and vomiting subside there may be a period of respite when the patient appears to get better. Unfortunately, if enough phosphorus has been absorbed into the bloodstream this is not the case; worse is to come.

From the intestines, the blood carrying the phosphorus will travel to the liver, where the phosphorus will accumulate. The liver is the main organ responsible for detoxifying the body. It is the first organ to receive blood that has come from the intestines, and is a kind of ‘clearing house' for anything entering the body through the digestive system. It filters nutrients from the blood, as well as waste products or harmful substances. Some harmful substances may be excreted without change because they are already sufficiently water-soluble to be passed in urine. However, white phosphorus is not soluble in water, so enzymes in the liver carry out chemical reactions to make it more water-soluble, so that it can be excreted. The products of these reactions, like phosphorus, are very reactive and cause damage to the cells in the liver. The liver will become enlarged and jaundice will become apparent as the basic functions of the liver break down.

Jaundice is characterised by a yellow pigmentation of the skin and whites of the eyes, and it is often a sign of liver disease. It is caused by increased concentrations of bilirubin, a waste product from the breakdown of red blood cells, in the body. Red blood cells are constantly being replaced, with the old ones broken down by the liver into bilirubin, which is transported to the bile duct to be excreted in the faeces.

The kidneys may also be affected by phosphorus, as they act as a filter, removing waste from the bloodstream into urine to be excreted, but it is not kidney failure that kills in this case. When the liver is damaged so badly that it is unable to function properly, the rest of the body is subjected to high levels of poisonous compounds. By this point there is very little that can be done to treat the patient, beyond supportive care. Death from liver failure ensues three or four days after phosphorus has been ingested.

Some real-life cases

There have been many real-life cases of murder and suicide by phosphorus, but a couple of cases have some interesting parallels with the plot of
Dumb Witness
. The book was written in 1937, and both of the following real-life cases occurred in the 1950s.

In 1953, Louisa Merrifield and her third husband, Alfred, moved in with 80-year-old Sarah Ann Ricketts as live-in housekeepers. Mrs Ricketts was healthy for her age but had trouble walking, and she seldom went more than a few steps from her front gate. She needed help with day-to-day activities such as cleaning, shopping and preparing meals. From the start it is clear that employer and employees did not get along, and Mrs Ricketts complained to friends and neighbours that she was not being given enough food.

At 6.30 p.m. on 13 April 1953, a doctor attended Mrs Ricketts and found nothing wrong with her, but the following day Dr Yule, her usual doctor, was called urgently. When he arrived shortly after 2 p.m. Mrs Ricketts was dead. Dr Yule could not account for her death, as he had not attended the patient recently in a professional capacity. However, he had spoken to her for fifteen minutes only four days previously, and she had seemed in her normal good health. Dr Yule declined to write a death certificate, and reported the death to the Coroner's office.

A post-mortem was ordered that revealed Mrs Ricketts's liver was ‘the colour of putty, with a cheesy consistency'
⁸⁴
consistent with phosphorus poisoning. The appearance of the liver confirmed that the poison had been administered recently, rather than in small quantities over a period of time. The pathologist could not confirm where the phosphorus had come from, but he suggested the most likely source was a tin of Rodine rat paste. The other ingredient in Rodine rat poison was bran that was mixed with the phosphorus; since bran was found in Mrs Ricketts's body and in close association with phosphorus, the pathologist believed the two must have been consumed at roughly the same time. No Rodine rat poison was found at Mrs Ricketts's bungalow or among the Merrifields' possessions. Rodine could be easily purchased from chemists, but even though it contained a lethal amount of phosphorus, there was no legal obligation to sign the poison register. The police therefore were unable to trace the purchase or any poison to the Merrifields.

However, an incriminating piece of evidence was found in Louisa Merrifield's handbag – a dirty spoon that had some congealed material stuck to it. It seemed an unlikely item to carry around in a handbag, but analysis of the congealed material revealed no trace of phosphorus. However, in the time between its possible use to mix the poison with food and its analysis in a forensic laboratory the phosphorus could have evaporated. It was suggested that the congealed material could have been jam, or it could have been rum and sugar, which Mrs Ricketts was known to take. Mrs Ricketts was also given brandy during her final illness by the Merrifields. Tests with brandy showed it was quite effective at masking the flavour of phosphorus, but it could not completely mask the smell; blackcurrant jam was effective at masking both the taste and the smell.

With clear signs of phosphorus poisoning at the post-mortem but no evidence of how it was administered or from where it had been obtained, it appeared that the case against the Merrifields was pretty thin. However, two weeks before her death and less than three weeks after the Merrifields had moved in, they had somehow persuaded Mrs Ricketts to
change her will in their favour. The day before she died a tradesman working in the bungalow heard Mrs Ricketts ask Alfred Merrifield to call at her solicitors as she wanted to change her will. She remarked to the tradesman, ‘They are no good to me. They will have to get out.' Louisa Merrifield also slipped up when she told an acquaintance that she had been living with an old lady who had died and left her a bungalow worth £4,000, even though Mrs Ricketts was, at that point, very much alive and in good health.

The jury deliberated for five and three-quarter hours before finding Louisa Merrifield guilty and Alfred Merrifield not guilty. Louisa was hanged, but Alfred was free to inherit a half-share of the bungalow left to him in Mrs Ricketts's will.

A second murder case shows how easily phosphorus poisoning can be mistaken for natural causes. In 1954, in a desperate attempt to avoid being forced into a second unwanted marriage by her parents, a young widow walked into a police station and confessed to murdering her first husband. She claimed that three and a half years previously she had given her husband phosphorus from a tin of rat poison. Initially the woman wasn't believed. Her first husband was thought to have died of natural causes, and she was not thought intelligent enough to have carried out the plan without being detected. Despite some misgivings the matter was investigated further, and it was found that the woman's husband, aged 35 when he died, had, until the day of his alleged poisoning, been in excellent health. The symptoms of his illness, attributed to haematemesis (vomiting of blood) from a gastric ulcer, included vomiting and severe abdominal pain before a brief recovery. Two days later the symptoms returned but worse than before, and they were accompanied by a great thirst. He died later the same day after vomiting large amounts of blood.

The body of the husband was reluctantly exhumed. It was felt that after three and a half years there would be little
evidence of poisoning remaining, but the body was in good condition and showed no natural cause for the symptoms displayed by the victim in his last few days. Tests on a number of organs and tissues, using the procedures outlined by Mitscherlich, confirmed the presence of elemental phosphorus. The court decided that murder had been proven, but the widow was not held responsible for her actions.

Agatha and phosphorus

In
Dumb Witness
, the death of Miss Arundell does not raise any suspicions with her doctor, family or friends, and is attributed to yellow atrophy of the liver, a condition she had been suffering from for several years. No one except Poirot is suspicious of the death; his real challenge is to prove that Miss Arundell was murdered. Agatha Christie highlighted the difficulty, which remains a problem today, of proving guilt in cases where the murderer has used poison. First, it has to be established that the victim did not die of natural causes.

The murderer in
Dumb Witness
chose their poison carefully. Jaundice is a symptom of phosphorus poisoning, and so mimicked a recurrence of Miss Arundell's liver complaint. Although the exact cause of Miss Arundell's complaint was never revealed, we know she had a near-fatal attack of jaundice eighteen months before she was poisoned. Miss Arundell appeared to have recovered from her earlier illness but was taking medication to manage her condition. She was also careful about what she ate and avoided rich foods, though she occasionally lapsed into bad habits. On the evening that Miss Arundell first developed symptoms of her final illness she had eaten a curry. The curry may have triggered an attack of liver trouble, but it would also have been the perfect vehicle for administering a poison such as phosphorus. The flavour of the curry would be strong enough to disguise the distinctive taste of phosphorus; curry can also be greasy, which would increase the rate of absorption of phosphorus into the bloodstream.

Anyone who eats a lot of phosphorus may excrete it unchanged in their faeces because it has stayed in the gut and
therefore hasn't been processed by the liver. This can result in ‘smoking stool syndrome', where white smoke emanates from a patient's waste as the phosphorus reacts with oxygen in the air. The faeces may even glow in the dark. Christie is too discreet to discuss something as unpleasant as the condition of Miss Arundell's bowel movements, but the fact that the doctor attending her never considered phosphorus poisoning indicates that Miss Arundell did not suffer from this condition.

A post-mortem examination would have been expected to reveal the true cause of death, but none was carried out because Miss Arundell was thought to have died of a known illness. Poirot considers having the body exhumed, but this would have been risky. It would have upset the family, and it would have been against the wishes of the deceased; plus it might not have led to any positive results after the body had been buried for two months. Phosphorus might leave clear signs of damage to the internal organs, such as haemorrhage or lesions from the corrosion caused by the phosphorus reacting with tissues in the body, but it might not. A large dose of phosphorus may be detectable initially by its characteristic smell when the stomach is opened; a pathologist may even be able to see the characteristic eerie green glow from the intestines if the lights are turned out. The longer the body has been buried, though, the more likely it is that the phosphorus has been converted into phosphate by reaction with oxygen. The glow would no longer be present, and phosphorus oxides from the poison would be indistinguishable from similar compounds naturally found in the body.

Damage to the liver is usually a better indicator of phosphorus poisoning, though probably not in Miss Arundell's case. Together with other indicators in the body, the liver can give clues as to when the poison was administered and whether phosphorus was ingested in a single large dose or in smaller doses over a long period of time. In the case of a very large dose of phosphorus, death may occur as rapidly as 12 hours later, due to the direct action of phosphorus on heart muscle resulting in cardiovascular collapse. If death had occurred
several days after ingestion, as in the case of Miss Arundell, the liver would be enlarged with signs of jaundice – the kind of damage you would see from a naturally occurring liver disease. The longer the victim survives after being poisoned, the more likely it becomes that the damage will spread from the liver to the kidneys, where phosphorus metabolites produced by the liver are filtered from the blood into the bladder for excretion in the urine. If the poisoning had been chronic and Miss Arundell had received regular small doses of phosphorus over a long period of time, her liver may have looked more like that of an alcoholic (i.e. enlarged with signs of jaundice), and therefore indistinguishable from the effects of her medical condition.