Science and the Criminal

by C. Ainsworth Mitchell

Before his death he was told that Mary had been putting poison into his food, and only said, “Poor love-sick girl. What won’t a girl do for a man she loves? I forgive her: I always thought there was mischief in these cursed Scotch pebbles!”

The scientific evidence at this trial was given in a very convincing manner by a Dr. Addington, who had attended the poisoned man and had examined the body and tested the white powder that had been sent by Captain Cranstoun. He stated that this was arsenic, and that he had found the same poison in Mr. Blandy’s gruel.

When asked in cross-examination why he believed this to be white arsenic he described the different tests he had applied to this powder and to a sample of pure white arsenic that he had purchased, and showed how the same results were obtained in each case, and concluded with the remark: “I never saw any two things in nature more alike than the decoction made with the powder found in Mr. Blandy’s gruel and that made with white arsenic.”

The judge in his summing up to the jury remarked that the case was one which was to be made out by circumstances. A great part of the evidence rested upon presumption, and if the jury regarded the presumption as a violent one, that is to say, one where the circumstances spoke so strongly that to suppose the contrary would be absurd, that amounted in law to full proof.

The jury, after deliberating for five minutes, found the prisoner guilty. She was executed on April 6th, and left a written confession in which she stated that she had not been aware that the powder she had given to her father was in any way noxious or poisonous.

Cranstoun was subsequently prosecuted and outlawed for his share in the murder.

If the scientific evidence in this early trial was a model of what such evidence should be, the same can hardly be said of that given at the trial of Katharine Nairn and Patrick Ogilvie at the High Court of Edinburgh in August, 1765, for the murder of Thomas Ogilvie, the husband of Katharine. They had only been married in January of that year, and it was at about the same time that Patrick Ogilvie, who was a lieutenant in the army, had returned from abroad. Almost immediately he supplanted his brother in the affections of his wife, and, a quarrel taking place between the two men, Patrick was forbidden to come to the house. Shortly afterwards the husband died, having shown symptoms of irritant poisoning.

According to the story of the prosecution, Katharine told a woman named Clark, who lived in the house with them, that Patrick had undertaken to procure poison for her, and that she was going to give it to her husband.

An unsigned letter to Patrick Ogilvie, alleged to be in the writing of Katharine, with reference to the poison, was put in as evidence.

Testimony was also given by a surgeon of Brechin that Lieutenant Ogilvie had obtained from him a small phial of laudanum which he said he required for his own health, and also half an ounce of powdered arsenic for the alleged purpose of killing some dogs that destroyed his game.