Why the nerve agent that poisoned the ex-Russian spy is so mysterious

On March 4th, former Russian double-agent Sergei Skripal and his daughter Yulia were found unconscious in Salisbury, England. They were the victims of an apparent poisoning. The poison was identified this week as a nerve agent called Novichok, part of a group of chemical weapons said to be extremely potent that we know very little about.Even before the lab results were out, it looked like the Skripals were the victims of a nerve agent: Yulia Skripal was unconscious, seizing, vomiting, and had l