On May 1, 1909 a fourteen-year-old boy named George Morris walked out of his father's house in East Perth and would not go back. He was found distressed in a West Perth street by his mother Sarah, who had been separated from his father for years, and she went straight to the Perth Police Court and applied for custody. The magistrate gave her temporary custody and declined to send the boy home.
What George then told the police became the case. He said that in April, after a cup of tea gave him a sore throat, Martha Rendell had painted his tonsils with something that frightened him, and that she had done the same to his brother and two sisters, all three of whom were dead.
Thomas Nicholls Morris had separated from his wife and had the children with him at 23 Robertson Street, East Perth, when Rendell moved in and passed herself off as his wife; accounts give the number as four or five. She had known him in Adelaide and followed him west, and the children were told to call her mother. Neighbors did not like her, and some told the police they had watched through the windows while she stood over a screaming child. The arresting officer, Inspector Harry Mann, later said she took pleasure in their pain. Those are police and neighbor accounts, and that dislike ran through everything that followed.
Annie Morris died on July 28, 1907, aged seven by one account and nine by another. Olive died that October, aged five or seven, on the 6th or the 16th. Arthur died in October 1908, aged fourteen or fifteen, on the 6th or the 8th. All three had been attended by doctors, more than one in each case. A Dr. Cuthbert certified the girls' deaths as diphtheria, and when Arthur died he asked for a post-mortem, which Rendell insisted on watching and which found nothing. Only one of the doctors ever expressed a doubt.
The inquiry was hampered by the time that had passed and by doctors' uncertainty about what swabbing with spirits of salts would do. But it was shown that large quantities of it had been bought while the children were ill and none since the last death. On July 3, 1909 the three bodies were exhumed. Diluted hydrochloric acid was reported on the throat tissue.
Rendell and Thomas Morris were both charged with murder and tried together before Mr Justice McMillan at the Supreme Court of Western Australia from September 7, 1909. Neither called evidence. On September 14 the jury convicted her and acquitted him. It was understood that he had been under her influence, though he had bought spirits of salts (one account says she did the buying) and had lied to the police and to the coroner, and the jury wanted to convict him as an accessory after the fact and was told it could not.
She was condemned for Arthur alone. The other two deaths were not charged, and after a trial the press covered in full she was popularly held responsible for all three.
She always said she had been treating the children for diphtheria.
A clemency campaign formed in the weeks before the execution, and it was not sentimental. It rested on the evidence. Hydrochloric acid is not the weapon of a poisoner, because it is neither quiet nor slow, and its action does not match the gradual wasting the children's doctor recorded. Diluted spirits of salts was in ordinary domestic use as a mild antiseptic and was applied to the throat for diphtheria, which came out after the trial rather than during it. A woman with no education would have had to calibrate the doses precisely enough to produce symptoms that deceived several Perth doctors across fourteen months. And Arthur was fourteen years old and would have had to submit.
None of that was answered. The campaign failed and she was hanged at Fremantle Prison on the morning of October 6, 1909, which on one set of dates was the anniversary of both Olive's death and Arthur's. She was thirty-eight, born on August 10, 1871, and she is the only woman ever executed there and the last woman hanged in Western Australia.
The public feeling around the case is part of the record. Crowds of Perth women gathered to demand her hanging. When the cottage was opened for the contents to be auctioned to pay for the defense, people walked in and took the household goods away as souvenirs, including the auctioneer's hat, and the sale raised ten pounds.
She was convicted of one murder on evidence that a substantial body of opinion, at the time and since, has regarded as insufficient. No court has ever revisited it.