Three members of the same family in a suburb of London, England, died of arsenic poisoning in 1929. The killer was never identified. It became one of the most notorious homicides – both in the United Kingdom and the United States. Scotland Yard, the London police service, was unable to identify the murderer in this Agatha Christie style multi-slaying within this respectable and much admired family.
So – who administered the toxic substance that robbed these people of their lives? Was it somebody within the family or a complete stranger – a serial killer even?
The three Croydon arsenic murder victims
Three people died within a tight time frame of arsenic poisoning. Who were they?
- Edmund Creighton Duff – Aged 59 at death, he was a retired British Empire official who had been High Commissioner of Nigeria, then ruled by Britain, married to the daughter of Violet Sidney.
- Edmund was therefore the son-in-law of Violet Amelia Sidney, aged 69, who was also murdered.
- The third victim was Vera Sidney, aged 40, another daughter of Violet, who never married.
As was so often the case with Victorian and Edwardian families, beneath the appearance of tranquil respectability was a seething cauldron of petty conflicts and slights. Violet was widowed. Her late husband – Thomas Sidney, a barrister – deserted her many years before, running off with his brother’s sister-in-law. Thomas was the son of a well-known politician of the same name who had been Lord Mayor of London in the 1850s. Violet never recovered from this betrayal and refused to marry again.
Salt was added to Violet’s emotional wounds when her daughter Grace wed Edmund Duff, a friend of her estranged former husband. In fact, while still alive, Thomas Sidney may have introduced Edmund to Grace. It’s been suggested that the family matriarch thought Edmund wasn’t of high enough social rank for her daughter. But that seems doubtful given that Edmund had been the High Commissioner of Nigeria.
Whatever the truth, Grace did her utmost to keep things cordial with Violet, visiting her mother most days. As for Vera, the 40-year-old daughter never married and lived with her mother, increasingly taking on the role of carer as Violet advanced into old age.
The family was spread across three houses in Croydon. Violet and her daughter Vera in one house, Grace and Edmund in another, and Violet’s son – also called Thomas, living with his wife, Margaret. The latter hinted at some animosity between her husband and Edmund. At all of these houses, doors were routinely kept unlocked and the inquest later surmised that if anybody had wanted to access a pantry to poison the occupants, it would not have been difficult.
How they died
Edmund Duff died on April 27, 1928, in a great deal of agony after returning from a fishing trip with a friend he had worked with in Nigeria: Harold Stanley Edwards. Edmund had taken a whisky flask with him on the trip and when he got back home, he drank beer during the evening before going to bed. The rest of the family may have taken a dim view of his drinking as they had all sworn off alcohol.
Within hours, Edmund was experiencing a very sore throat, vomiting, and diarrhoea. Grace called the family doctor, Robert Elwell, who prescribed aspirin and quinine. It took over a day for Edmund to die. Elwell and another medical colleague were present at the end, still baffled by what had happened. That confusion extended to the autopsy where, despite the organs being examined, no arsenic was identified. His death was blamed on “ptomaine” poisoning – basically, food poisoning. But the food was not the culprit – the arsenic had been administered in the beer.
Nearly ten months later and the hapless Dr Elwell was called to the house of Vera and Violet Sidney. Vera had been feeling unwell for days but it was a bowl of soup prepared by the housemaid, Kathleen Noakes, which tipped her over the edge. Nobody ate the soup except for Vera, Kathleen (who had a spoonful), and their cat, Bingo. They all fell ill but it was Vera who suffered convulsions and nausea. This time, Dr Elwell misdiagnosed gastro-intestinal influenza. Vera died shortly afterwards.
Then her mother, Violet, expired the next month, after taking some medicine, administered by Kathleen Noakes. Again, Dr Elwell failed to detect the hand of a murderer. He did make some inquiries from the chemist about the ingredients in the medicine but, by the time Scotland Yard got involved, the medicine bottle disappeared. Few doubted they were now looking at multiple murders.
The three family members were given Christian burials in a local churchyard – but they would not rest in peace for long.
Exhuming the corpses
Gossip and rumours spread like wildfire. So much so that the Home Office (the British interior ministry or equivalent of Homeland in the US) ordered the bodies to be exhumed. Home Office pathologist Dr Roche Lynch found arsenic in Edmund’s corpse.
The Croydon coroner, Dr Henry Beecher Jackson, issued a 150,000 word report, concluding the trio died from arsenic poisoning. But, he made the unusual decision to explicitly state that “there is no evidence in my opinion which singles out any one member of the family as the poisoner”.
Coroner Jackson held at least 26 sittings to examine the murders. As publicity grew, top criminologists from Scotland Yard attended, as did the leading Home Office criminal pathologist, Sir Bernard Spilsbury. Born in 1877, Spilsbury was a man who dominated inquests during his courtroom appearances. This celebrity scientist had guaranteed Doctor Crippen’s conviction, which resulted in the villainous doctor being hanged for killing and dismembering his wife. Spilsbury also revealed the truth in the Brides in the Bath murders perpetrated by the serial killer, George Joseph Smith. Sadly, Spilsbury committed suicide in 1947.
During the 1929 inquest, Spilsbury gave his considered opinion that the arsenic in these murders had been administered in the beer drunk by Edmund and the medicine drunk by Violet. When diluted in this way, he declared, arsenic loses its distinctive taste.
Witnesses and suspects
The two principal witnesses at the inquests were Edmund Duff’s widow – Grace Duff – and Violet’s son, Thomas Sidney. To many who have analysed these multiple murders, Grace emerges as a credible suspect, not least because she benefited from her dead husband’s life assurance policy. She bought their house with the proceeds.
During the inquest hearings, the coroner and chief detective received death threats by letter. Grace and Thomas also got similar correspondence. Who wrote these death threats remains a mystery. In August 1929, the inquest into the poisoning of Edmund Creighton Duff concluded that it was “wilful murder by person or persons unknown”. All the inquests failed to identify a suspect.
One jury wanted to include a statement condemning the initial botched Edmund Duff autopsy: “We consider that the chemical analysis of the organs carried out after the first post mortem examination was not conducted with sufficient care”. The coroner, however, refused to include this statement into the final judgement, making the rather cryptic comment: “I think possibly at a later date you may be rather glad I have done so.”
So who committed these murders by arsenic in Croydon? There were different theories:
- Dr Elwell was rumoured to be having an affair with Grace Duff. Did he remove Edmund to enable the two to marry? But why kill Violet and Vera?
- Did Violet murder Edmund, who she secretly despised? But why kill her beloved Vera?
- Thomas Sidney junior, the brother of Grace, had to clear his name with Scotland Yard and the police could find no credible motive. It was pointed out that he did have weed killer in his garden shed that contained arsenic.
- One historian has argued that Dr Elwell was correct about Edmund and Vera – no foul play was involved. As for Violet, consumed with grief, she committed suicide.
Grace Duff is the most likely candidate for murderer. But the case against her is not conclusive.
Before the murders, Grace had inherited wealth but her husband had gambled it away on the financial markets, thinking he was a canny investor. In truth, Edmund was a man whose life was on a decidedly downward trajectory. The couple had been forced to downsize and get used to living within a more modest budget. Desperate to maintain her social position, had Grace decided to bump off her husband, mother, and sister – to secure a windfall?
There is another death, unmentioned so far, that points to Grace. Back in 1927, she and Edmund took in a wealthy lodger – Anna Maria Kelvey – who then suddenly died leaving gifts in her will to Grace’s children. After the three family murders, a lawyer for the Sidney estate described Grace as the “devil incarnate”.
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Edgar Wallace investigates
As 1929 came to a close, Scotland Yard was still without a suspect. The British crime writer Edgar Wallace weighed in describing Grace as “the aesthetic, clear-eyed woman of 40” who was “the pivotal point in a circle of cold-blooded murders which removed her mother, her sister and her husband, in every case by arsenical poisoning, in every case in coincident circumstances”.
Wallace argued that poison is something that has to be administered at close range and that the murderer is normally on intimate terms with the victim. All three family members were already ill to some degree before the fatal dose was administered. Even the athletic Vera had been overwhelmed by fatigue in the days leading up to her death. That meant they all needed some degree of care and assistance. The murderer had deliberately weakened them before dealing the final blow.
However, there was no great financial gain that would justify murder, Wallace concluded. Nobody won a big fortune out of these killings. For some reason, he added, poison cases always seemed to be accompanied by threatening letters, so that element did not surprise him. Wallace ruled out the involvement of servants. He was convinced the killer was a respectable figure and furthermore, he was sure they had an accomplice.
Wallace added that while he was not being fed information by the police (which he clearly was), the focus of the investigation was on Edmund Duff, as opposed to Violet or Vera. Scotland Yard thought this was where they could find the damning evidence. But as things turned out, they drew a blank.
This remains one of England’s most perplexing unsolved murders. As an attractive, eloquent, and sometimes emotionally cold woman, Grace Duff has been implicated by many commentators. But the evidence and motive is weak. It remains a mystery to this day.
It sounds like it could have been the cook possibly.