Herbert Rowse Armstrong, 53, was a lawyer in Hay-on-Wye, Herefordshire. In October 1921 he became involved in a dispute with a rival solicitor in the town, Oswald Martin. To resolve this Armstrong invited Martin to his home for tea. After the visit Martin became ill, and when his urine was examined it was found to contain arsenic.
The police were informed, and the death six months earlier of Armstrongs wife Katharine was recalled, and her exhumation was ordered. An autopsy revealed a large quantity of arsenic, and detectives learned that in July 1920 Mrs. Armstrong had made a will leaving her whole estate to her husband. The following month she had become ill, and was certified insane and removed to an asylum. She had returned home in January, only to die on FEBRUARY 22nd, 1921, of an agonising complaint diagnosed at the time as gastritis.
Charged with her murder after arsenic was discovered in her body, Armstrong pleaded not guilty at Herefordshire Assizes. The defence claimed that she had taken the poison herself. But the prosecution showed that she was too ill to do this throughout the four days prior to her death, and the lethal dose must have been administered within 24 hours of her demise.
Armstrong was proved to have made several purchases of arsenic, and the poison was found in his home and in his pocket when he was arrested. Unaware that he was being investigated, he had invited Martin to come again for tea!
Convicted of his wifes murder, Armstrong was hanged at Gloucester Prison on May 31st, 1922.