On 23 November 2006, the Russian KGB agent Alexander Litvinenko died in a London hospital. He had been poisoned three weeks previously, allegedly by former colleagues. But what is interesting was the poison used – it was a radioactive isotope known as polonium-210.
This was no common poison, but a radio-isotope that could only have been produced in those quantities inside a nuclear reactor. It took several weeks to detect, by which time, it was too late to do anything to save Alexander.
Poisonings have occurred for as long as history itself, with the poisoner trying to outsmart the victim and the authorities. A poison often used over the centuries is arsenic trioxide. It only requires tiny quantities to kill, less than two tenths of a gram can be fatal, it is soluble in water and has no taste or smell.
This was used by Agrippina, the murderously ambitious niece and later wife of the Roman emperor Claudius. She poisoned her uncle/husband in order to install her son, Nero, as Emperor of Rome.
It seems unlikely that Agrippina was concerned about detection. However, other poisoners have exploited the non-specific symptoms it causes; in making arsenic-induced death seem natural.
In the late 19th century, Mary Ann Cotton, a woman from county Durham, mysteriously lost about 20 members of her own family. Most died from what was believed to be gastric fever, or typhoid as it is now known. They all suffered symptoms of abdominal pain, diarrhoea and fever, which are consistent with typhoid but also of arsenic poisoning.
It wasn’t until she attempted to give her stepson away to the workhouse, and when they refused to have him and he subsequently died, that people started to ask questions. Was it coincidental that all the members of her deceased family were heavily insured?
Suspicions persisted and some early forensic analysis subsequently found the presence of arsenic in her stepson’s body. Mary Ann Cotton was convicted and hanged for her stepson’s murder.
Other murderers have used poisons which at lower doses have a therapeutic use. The famous murderer Dr Harvey Crippin poisoned his wife Belle with the drug hyoscine. In small doses, this has been used to treat insomnia, travel sickness, drug addiction and depression.
However, as a very bioactive compound, Harvey Crippin recognised its potential in disposing of his wife, believing that the death would be regarded as natural causes.
Things did not go to plan and he was forced to try and dispose of the body. This proved to be his undoing and he was hanged for his wife’s murder on 23 November 1910.
Perhaps the most notorious poisoner of recent times is Dr Harold Shipman. No-one knows how many people he murdered, but it's believed it may be as many as 250. His murder weapon of choice was the drug diamorphine, also known as heroin.
This is widely prescribed for patients in severe pain, for example, if suffering from terminal cancer. So what better way to get away with murder than to have relatives praise you as a caring doctor alleviating pain?
But greed got in the way and it was only when victims’ wills had been changed in Shipman’s favour that questions started to be asked. Shipman never did confess to murder and committed suicide in prison in 2004, after his conviction for the murders of just 15 of his victims.
As a result of the Shipman case, wide-ranging legislation was introduced in an attempt to ensure that this was never repeated. This included changes in the certification of death by doctors and the assessment of healthcare professionals to prove fitness to practise.
Of course, it is now very difficult to get hold of poisons such as arsenic and polonium-210. So next time someone makes you a cup of tea, try not to wonder exactly what is in it.