Picking Your Poison

Guest Post by K. K. Cathers –

Throughout history, poison has fascinated and terrified us in equal measure, both in the real world and in the worlds that authors create.

A good poisoning can make for a great murder mystery, and, in this instance, authors of historical fiction are spoiled for choice. There is hardly a kitchen cupboard, bedside table, workplace, local grocer’s, or druggist’s that doesn’t contain poison. And lots of it. For the entirety of the nineteenth century and the first part of the twentieth, it was frighteningly easy for people to get their hands on poison. (Legislation existed, but often wasn’t adhered to or enforced.)

When planning a (fictional) poisoning, it’s tempting to look at exotic or unusual poisons (urari, Upas Antiaris, or Calabar beans; all of which had nineteenth-century treatises written about them). Or to find something difficult to detect. Or something which fits the timeline you’ve devised. If you choose based on these alone, it can lead to a lot of headaches when trying to bring your villain to justice. Care must be taken when deciding how you’ll do away with your (fictional) victim. It’s far too easy to focus on the murder and ignore everything that comes after it. If you’re not careful, you’ll end up with a murder that’s impossible to solve, and, in some instances, one that’s impossible to detect.

How do you pick your poison? Before coming to a final decision, take the following into consideration:

1. Are you going to take your murderer to court? This is the first question that requires an answer; before you even flip through books of poisons. If your answer is “Yes,” then there is a whole slew of poisons that could be eliminated depending on the year when your story is set. Check the date at which toxicology becomes available for the poison you are interested in. If it’s after the date in which your story is set, you can’t use it. Why? Because if the prosecutor cannot say for definite there was poison in the body, you cannot prove poison was the cause of death. No poison, no murder.

One way around this is using a poison in solid form (antimony or arsenic, for example). In this instance tests will be done on the undigested particles found in the stomach or intestines. Having said that, if your poison is too exotic, there won’t be a chemical test available to tell them what the particles are, or if they’re even poison.

If your answer is “No,” and you won’t take your villain to court, then you have a wider choice of poisons. In this instance, you can do what Agatha Christie sometimes did. You provide enough proof for the reader to be convinced, but not enough for a conviction. Rather than trial and execution, justice is served when your villain commits suicide or dies by someone else’s hand. But, beware. The more exotic the poison, the less likely anyone will recognize the death as nefarious.

2. How will the death be recognized as murder? Poison is unlike other methods of murder. If you find someone with a gunshot to the heart or a knife in their back, it’s obvious the death was not natural. When someone gets sick and dies, no one’s default presumption is poison, not even today. That means the first thing you have to do is prove the victim did not die of a disease or physical condition, such as a bad heart. In an era when disease and poor health were rampant and medical knowledge was in its early stages, this is not easily done. The more exotic the poison, the less likely someone will recognize its symptoms. This doesn’t eliminate the rarer ones, but it does require some fiddling which I’ll talk about in the next section.

Things have changed in the war against poison since 1800, but what has remained the same is how the crime was detected: symptoms, and behaviour of those around the victim. Sometimes together, sometimes separately. If you choose a common poison, then both options are available. If exotic, you only have the behaviour of those close to the victim. Don’t let this discourage you. The conviction of William Palmer in 1856 was done entirely on circumstantial evidence.

One bonus (depending on how you look at it), with circumstantial evidence alone, there’s a good chance you’ll get to write in an exhumation scene.

3. Who is going to recognize the death as murder by poison? If your poison is one of the “old faithfuls” you only need to have a physician recognize the symptoms. If not, you will have to create a character who has personal experience with the poison you have chosen. Dr Henry Letheby was one of the few physicians who could, without doubt, immediately distinguish between arsenic poisoning and Asiatic Cholera. While in India he had treated hundreds of cases of the latter, to the extent that he knew arsenic from Asiatic Cholera merely from a description of the victim’s symptoms.

If you use a little-known poison from elsewhere in the world, you must create a character who either has a large collection of treatises on poisons, or who visited or studied in the area where your poison originated. You can use urari, just make certain one of your characters had spent time in British Guiana.

It isn’t necessary to have everything plotted and finalized before you go looking for your poison, but it is advisable to consider how you’ll prove it was murder and who did it, before you choose your weapon.