In olden times, kings and queens had royal poisoners on hand to get rid of inconvenient people. They were good at what they did. For example, they could lightly dust a letter or page of a book with a powder that would kill whoever touched it.

Politically-motivated poisoning is back in vogue. New York reports that "Kim Jong-nam, the older half-brother of North Korean leader Kim Jong-un, was killed in a Malaysian airport Monday after he was sprayed in the face with an unknown liquid, police said Tuesday."