BANGKOK: From the courtiers of Ancient Greece to Soviet spies and maybe now North Korean agents, poison has a long history as a weapon of murder, favoured by assassins for its stealthy delivery of the fatal blow.
The killing of Kim Jong-Nam, the half-brother of the North Korean leader, at a Malaysian airport has revived fascination in the poisoner's methods.
In a story that could be cribbed straight from a spy novel, intelligence chiefs in South Korea say female agents dispatched by their secretive northern neighbour administered the lethal dose, with reports suggesting a toxin was sprayed in his face.
Half-brother of N Korean leader Kim assassinated in Malaysia
An autopsy was being carried out Wednesday.
A would-be poisoner can choose from a catalogue of deadly chemicals, some of which are relatively easy to obtain.
Ricin - naturally occurring in castor oil plant seeds - and thallium (rat poison) are notorious for their murderous properties.
Arsenic delivers a slow and miserable death, while strychnine induces extreme body spasms as the victim's respiratory system collapses.
But "cyanide is the fastest killer and the easiest to detect, its pathology appears all over the body," said Porntip Rojanasunan a forensic expert and adviser to Thailand's Justice Ministry.
She said the victim's "bright red blood" in post-mortem is the telltale sign of a potential cyanide poisoning.
Other chemicals such as potassium can cause "an extreme heart arrhythmia.. and can lead to a heart attack very quickly."
Slow-acting poisons may allow assailants to slink away from the crime scene undetected.
South Korea suspects female assassins killed half-brother of North Korea leader
Tales of poisonings - real or imagined - have formed their own mythology.
Poisoning has become a byword for backroom scheming by treacherous political rivals, revenge and cold-blooded murder.
Shakespeare took to the theme, with a penchant for poison-tipped endings for his characters, while Snow White's demise after eating the poison apple became a cautionary tale on jealousy.
In real-life, academics still debate whether it is was arsenic or the asp that did for the Cleopatra, toxic wine that killed Alexander the Great or poisonous secretions in his wallpaper that accounted for Napoleon.
Anguished housewives of Victorian Britain earned notoriety for dosing the food or drink of brutish husbands with arsenic.
More recently poison featured prominently in Soviet-era tradecraft.
In 1978 Bulgarian dissident Georgy Markov died after receiving a fatal dose of ricin delivered through the tip of an umbrella on a London street.
His killer has never been caught.
North Korean leader’s half-brother pleaded for his life: Seoul MPs
Moscow was accused of carrying out an assassination on British soil in 2006 when tea laced with highly-radioactive Polonium-210 was served to ex-Russian spy Alexander Litvinenko, condemning him to a slow death.
In Asia, members of a shadowy Japanese cult dropped plastic bags of liquid sarin, a nerve agent, on packed Tokyo subway trains in 1995, killing more than a dozen people.
Nine years later Indonesian rights campaigner Munir Said Thalib was killed after being poisoned on a flight from Jakarta to Amsterdam.
If Seoul's spy chief is right, North Korea now appears to have added a new chapter to the chilling history of poison.