The unsolved poisoning of three victims in South Croydon, England, during 1928 and '29, involved two interrelated families, the Sydneys and the Duffs. No motive was ascertained in the crimes, and at this writing no suspect has been identified.

First in the series of victims was Edmund Creighton Duff, age 59, the son-in-law of elderly Violet Sydney. Returning to his Croydon home on April 26, 1928, at the conclusion of a fishing holiday, Duff complained of nausea and leg cramps after eating supper. His condition worsened overnight, and he was pronounced dead on April 27. An autopsy yielded negative results, and his death was ascribed to unknown "natural causes."

Ten months later, on February 14, 1929, Vera Sydney, Violet's 40-year-old daughter, remarked on feeling "seedy" after lunch. The cook, her mother and the family cat all suffered after sharing in the meal, but they recovered, whereas Vera steadily declined. She died on February 16, after hours of cramps and vomiting, which her physician blamed on "gastric influenza."

Violet Sydney was the last to go, falling ill after lunch on March 5. Already under medical care in her bereavement, she died hours later, blaming the "gritty" tonic prescribed by her doctor. An analysis of the medicine showed nothing out of place, and the cause of Violet's death remained a mystery.

Surviving relatives demanded an investigation, and the female victims were exhumed on March 22, 1929, an autopsy revealing traces of arsenic in both bodies. Edmund Duff was exhumed, over his widow's protest, on May 15, and this time arsenic was found, the discrepancy "explained" by a suggestion that physicians may have analyzed organs from the wrong corpse in 1928. Inquests on Duffand Vera Sydney attributed their deaths to murder by persons unknown; in the case of Violet Sydney, there was insufficient evidence to tell if she was murdered or committed suicide. In either case, the mystery remains unsolved.