I received an urgent message, delivered by a mounted courier, from the pen of my colleague, Dr. Pekel, and calling for my witness to an examination of the body of a woman found in the waters of the Venetian canal.

It was my initial suspicion that this person might have drowned, but the good doctor pointed to discoloration of the body unnatural in either salt or fresh water drowning and to other signs that may indicate foul play.

Discoloration was present across the entire skin and thus cannot be attributed to makeup or a topical treatment.

The blood, too, was discolored, presented as a odd pink. This is not due to a contamination of the blood with water as a result of drowning, as some unfamiliar with the writings of Galen, Vesalius, and of the brilliant Dr. William Harvey, physician to both King James and King Charles I of England, might suggest. Instead, it points to an imbalance in the body prior to drowning, one that would likely prove fatal.

To test this hypothesis, after the good doctor Pekel sectioned the stomach and bowel with great precision, I removed a sample of the contents for further testing. It was clear to him from examination of the lining of the stomach that this was indeed a poisoning. He could narrow down the type of poison to a very short list.

The initial test to precisely identify the poison at work was simply to float the sample of the excrement in a bucket of water and carefully stir it until its elements came apart each from the other, the heaviest to fall to the bottom and the lightest to float to the top. Each group was then removed, strained through a cloth to remove water, and visually inspected. There was no question regarding the presence of arsenicum, yellow orpiment, among the heaviest precipitants. This is a metallic element, derivative of iron, thus weighty.

Arsenic may be an ingredient in some ladies' makeup and is also prescribed occasionally in tiny doses for some complaints, though I do not personally believe it is of much therapeutic value. The amount present, however, was extraordinary and could not have been incidentally introduced or prescribed without malice. It is a lethal dose, indeed it is a fatal dose several times over. It is as the doctor suspected, an incident that can only be described as wilful murder by poison.

God is my witness that I have acted in good faith here and spared no pains to uncover the facts. The deceased woman is far beyond any salvation offered by the medical arts. The application of science may, though, play a role in bringing the facts to light and a killer to justice.