Well the South Koreans are one step closer to knowing after they caught a North Korean agent in the middle of an assassination attempt in Seoul, South Korea.
All you might feel is someone brush by you and a slight pin prick. But very quickly you would be suffering muscle paralysis followed by suffocation. You would be dead within a very short period of time.
This is the deadly effect of just one of the weapons found on a failed North Korean assassin last year on the busy streets of Seoul, now shown exclusively to CNN.
Disguised to look like a Parker ballpoint pen, it contains a poison needle and is practically impossible to identify as a weapon.
The second pen shoots a poison-filled bullet which penetrates the skin and releases the toxin and the third weapon is a flashlight, loaded with up to three bullets. They all look completely innocuous but all three will kill.
source : http://edition.cnn.com/