Today the news is reporting that Malaysia has identified the poison used to kill Kim Jong Nam.
VX Nerve agent. An extremely potent chemical weapon with pretty dire consequences. VX nerve was specifically designed to deny large areas of ground to an opposing army, forcing them to live in protective gear and become about 10% effective. Essentially any army hit with VX would suffer immediate casualties of around 80% then have to leave the area.
VX eventually evaporates and is equally lethal in gaseous form as it is in liquid form. Everything the assassins touched, the receptacle they kept the nerve agent in and anything that Kim Jong Nam touched on the way to hospital is now contaminated and a possible source of further injury.
This is one of the nastiest chemical weapons on the planet. So bad that Americans said "use it and we nuke you".
Using VX in an assassination is a very concerning thing. This kind of weapon is absolutely NOT discrete and should never have been released in a public area. The fact that it was used and released where it was, says a lot about the regime which authorised it.