I’m continuing my examination of major Victorian murder cases brought about by poisoning. A new one every Monday! These posts were inspired by Kathryn Harkup’s book A is for Arsenic: The Poisons of Agatha Christie (2015), from which I am quoting below.
Today let’s talk about digitalis, a poison that can be extracted from foxgloves.
Harkup discusses that one of the benefits of poisoning someone with digitalis is that it kills largely without leaving a trace, unlike some other substances which make it very apparent that a victim has been poisoned. As such, deaths by digitalis have either been 1.) very rare or, more likely 2.) been considered unsuspicious, natural-seeming deaths and therefore haven’t been investigated.
Despite the fact that digitalis leaves a victim dead without too many signs of poisoning, “a large dose would be detectable if the pathologist knew to look for it. The presence of digitalis was first detected in a murder victim in 1863; scientific evidence helped convict Dr Edmond-Desire Couty de la Pommerais of the murder of his former mistress, Madame Seraphine de Pauw.
“Pommerais had convinced Pauw to take part in an elaborate insurance swindle in order to pay off his debts. A number of large insurance policies were then taken out on Pauw’s life. Pommerais told her that his plan was to convince the insurance companies that Pauw had a terminal illness and would die soon, at which point they would claim a large annuity until she died rather than pay out the vast sums of insurance money. She would then miraculously recover to live the rest of her natural life in financial security. Seraphine even told her sister of the ingenious plan; but the sister saw through Pommerais’s promises, and warned Seraphine that he might be planning to kill her keep all the money for himself.
“This is exactly what happened. On 16 November 1863, Pommerais gave Pauw something that made her very ill but, as was predicted by her sister, Madame Seraphine did not recover. Pommerais filed his claims with the insurance company and sat back, presumably reassured that the poison he had chosen to kill his victim could not be traced. The police, however, were suspicious of Pommerais’s behaviour; they asked Ambroise Tardieu (1818-1879), a respected medical doctor, to analyse Pauw’s body for signs of poison.
“After eliminating metals such as arsenic and lead, Tardieu turned to the alkaloids. Using the Stas method [which Harkup discusses elsewhere in the book], Tardieu managed to extract a bitter-tasting substance from Pauw’s remains. However, Tardieu could not identify the substance; it was not an alkaloid with which he was familiar. After a series of fruitless experiments, and almost at his wits’ end, Tardieu decided to inject five grains of the extract (approximately 300mg) into ‘a large vigorous dog‘ to see what would happen.
“The answer was – absolutely nothing, for two and a half hours. Then the dog suddenly vomited and lay down, obviously weak. The dog’s heart slowed, beat irregularly and occasionally stopped until twelve hours later, when the beast began to recover. Looking at correspondence between Seraphine and Pommerais, Tardieu found discussions of a prescription of digitalis she was taking to ‘ stimulate herself’. This had all been part of the ruse to obtain money from the insurance companies, but it gave Tardieu the clue he needed – the victim had died from digitalis poisoning.
“Tardieu had not recovered enough digitalis from Pauw to account for her death. He explained to the police inspector that what he really needed was a sample of her vomit; this would contain a much higher concentration of the poison, enough perhaps for him to establish a cause of death. The inspector responded to this in a remarkable way. No samples of vomit had been retained, so he went back to Pauw’s bedroom, and removed floorboards and wood shavings from parts of the floor where vomit had been spilled. Tardieu quickly set about analysing the samples sent to him, and obtained far greater quantities of the poison from the vomit that had dried onto the floor.
“To prove the poison was the same as that found in the body, Tardieu observed the effects of the extracts from the floorboards on frog hearts, where he witnessed the same reduced heartbeat. He carefully repeated his experiments, and requested more samples of floorboards from under the bed, where no vomit could have reached – Tardieu wanted to ensure that the effect on the frog hearts was being caused by the poison, and not by varnish or paint from the floor. At the subsequent trial Pomemrais’s defence team attempted to discredit the scientific evidence Tardieu presented, but it was compelling; Pommerais was executed for his crimes” (105-06).