If you’ve been paying attention to my blogs over the last three weeks, you’ll notice that I’ve been writing about some classic poisons that have been used throughout history as murder weapons and which have been the lethal elements of choice in a variety of murder mysteries.

Today’s posting rounds out those recent blogs, as well as others that I’ve written in the past, to complete a collection of discussions on the world’s most famous poisons. The list includes aconite, arsenic, belladonna, botulinum toxin, dimethylmercury, elemental mercury, hemlock, polonium, tetrodotoxin and now cyanide. Hyperlinks are provided to those blogs as a reference.

Cyanide is a dramatic killer. As little as 100mg can be lethal, and it’s a rapid kill. Death can occur within a minute or up to 15 agonizing minutes, depending on the dose and the method of administration.

This poison was first used as a chemical weapon in the form of a gas during World War I and later in the Nazi gas chambers during the Holocaust. In the 1980s, it was used on the Kurdish inhabitants of northern Iraq during the Iran-Iraq War.

It became a famous method of murder in mystery novels (think Agatha Christie) and various spy novels in which captured spies commit suicide by swallowing cyanide pills.

Cyanide exists as a gas, a liquid or in solid form. Hydrogen cyanide liquid is extremely volatile, however, and boils off (vaporizes to a gas) at warm room temperatures (78.1˚F / 25.6˚C). The liquid is almost colorless to a transparent pale blue color. It gives off a bitter almond smell (a sweet cherry-like smell) that is so faint some may not even be able to detect the odor.

Solid cyanide exhibits in crystalline form, mainly as sodium cyanide or potassium cyanide, but the crystals are so fine that they appear to be a white powder.

Poisoning with cyanide may be a difficult crime to detect. The effects of cyanide poisoning exhibit as suffocation, with initial symptoms similar to the shortness of breath climbers or hikers experience at high altitudes.

This happens because cyanide prevents the cells of the body from being able to use oxygen. It inhibits an enzyme in the mitochondria of cells from doing its vital job of capturing oxygen and transporting it into cells.

The initial symptoms of cyanide poisoning include general weakness, shortness of breath, confusion, headache, dizziness, excessive sleepiness and bizarre behaviors. The symptoms progress to seizures, coma and eventual death.

An acute dose of cyanide will have a dramatic and rapid onset. It immediately affects the heart and the victim suddenly collapses, as in a heart attack. When the poison is circulated to the brain, seizures and coma precede death.

Chronic cyanide poisoning with low doses over a longer period of time, however, will exhibit these same symptoms, but the onset is much more gradual and is dose dependent.

The most notable telltale sign of cyanide poisoning is an unusually pink color to the victim’s skin (or even cherry-red) because oxygen remains in the blood rather than transferring to the body’s cells. The body is simply starved for oxygen. The victim may breathe rapidly and have an initial fast heartbeat that slows as oxygen starvation progresses.

Another unique sign of cyanide poisoning is that the victim’s breath may smell faintly like bitter almonds, but it may be so slight that this evidence might be overlooked.

Cyanide is present in many common substances found around the home: almonds, apple seeds, apricot kernels, some insecticides and pesticides, and it is plentiful in tobacco smoke.

A common accidental cyanide poisoning occurs with house fires. The victims are overcome by smoke inhalation while common household items like rubber, plastics and silk burn and create cyanide fumes.

So for an easy to use, difficult to detect, rapid and very effective poison, there is nothing sweeter than cyanide. But be sure to look for that telltale bitter almond smell on the victim’s breath and notice their rosy pink complexion.

Thoughts? Comments? I’d love to hear them!