A favorite of mystery writers, suicidal Nazis and homicidal nobles.
Occurring naturally in the fruit stones/seeds of Apples, Peaches, Mangoes and Apricots, cyanide took its name when the dye Prussian Blue was accidentally created, containing iron and a then unknown agent-cyanide. The iron-containing compound was named ferrocyanide, or, 'blue substance with iron'... and when the compound was analyzed and the iron removed, the resulting leftovers were cyanide.
The world of mystery literature is dotted with this bitter almond-flavored poison and the killers' continued attempts to disguise the poison's almond flavor and aroma.
A quick way to end one's existence and prevent the "imagined horrors worse than death," it was nothing for this handy little poison, in capsule-form, to find its way crushed between the teeth of those fleeing capture and torture. The Goebbels fed the capsules to their five children before taking their own lives. Even the Fuhrer, himself, made use of the handy suicide pill.
Cyanide is pretty lethal, pretty quick. Though, there's been at least one case of deliberate cyanide poisoning that's baffled historians-- that of The Mad Monk, Rasputin, mystic and healer to the Romanov household during the reign of Tsar Nicholas II.
When Rasputin's intentions were believed to be a threat to the Romanov's power, plans to do-away with the Monk by a group of nobles and politicians were formed. Though, after being fed enough cyanide to kill five men, with no sign of the poison slowing him down, his would-be executioners were forced to try several more drastic measures to rid Russia of one of its threats.
Sleep now, hear not the morning's call,
close your eyes against the night,
feel my hands hold you tight,
hush now, make no whispered sound at all.
Think not, of bad dreams that might come,
sip the last of bitter tea,
cling once more, my love, to me,
fear not, all your troubled days are done.
--- e.a.s. demers