Croydon Poisoning's

Surrey, 1928. Over a period of a year, three members of the same family -- a retired colonial administrator, his wife's sister and his wife's mother -- were poisoned in their homes. The murderer must have been one of the family, but no one was ever charged.

26th April 1928, First in the series of victims was Edmund Creighton Duff, aged 59, the son-in-law of elderly Violet Sydney.
Returning to his Croydon home after a fishing holiday, Duff complained of nausea and leg cramps after eating his supper.

27th April 1928, His condition had got worse overnight, and he was pronounced dead.
An autopsy was inconclusive,  his death was attributed to unknown natural causes.

14th February 1929, Ten months later, Vera Sydney, Violet's 40 year old daughter, remarked on feeling a bit "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.

16th February 1929, Vera died, after hours of cramps and vomiting, which her physician blamed on "gastric influenza."

5th March 1929, Violet Sydney was the last to die, falling ill after lunch.
Already under medical care for 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.

22nd March 1929, Surviving relatives demanded an investigation, and the female victims were exhumed, an autopsy revealing traces of arsenic in both of the bodies.

15th May 1929, Edmund Duff was also exhumed, despite his widow's protest.
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 Duff and 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 had committed suicide. In either case, the mystery remains unsolved.