These he had sent to Katharine, who was believed to have put the arsenic in her husband’s tea.
The defence was that the deceased had died a natural death, and that Katharine Nairn was in the habit of taking small doses of laudanum and of salts for her health. Expert evidence was given on her behalf by a Dr. J. Scott to the effect that “he had made experiments upon arsenic and knew well that it would not dissolve in warm water.”
The evidence, which by the way is incorrect, went to prove that even if arsenic had been introduced into the tea it could not have caused death by poisoning.
A surgeon also gave evidence that the symptoms might have arisen from natural causes.
For the prosecution no proof of the powder being arsenic or that the husband had really died of arsenical poisoning was given, and no post-mortem examination was made.
The counsel for the defence put the position in the following form: “The incest is supposed to be certain because the husband is supposed to have been poisoned; and, on the other hand, the man is believed to have been poisoned, because there is supposed proof of incest.”
Both prisoners were found guilty and sentenced to death, but the execution was delayed pending an appeal to the Privy Council in London. The sentences were confirmed and Patrick Ogilvie was executed in November, but Mrs. Ogilvie, who was expecting the birth of a child, was kept in prison. A daughter was born early in 1766, and Katharine Nairn managed to escape from prison in March of that year.
The trial curiously foreshadowed the trial of Mrs. Maybrick a century later in many of its features, and, as in the modern case, convincing proof of guilt was wanting.
The question whether a particular substance is or is not a poison has frequently been raised in a court of justice, and on several occasions a prisoner has owed his acquittal to a conflict of scientific opinion upon the point.