the candid and chilling hour, he gives his opinion on why he thinks other young deranged men commit mass shootings, it's a fascinating interview. that's the piers morgan live special friday night. that is all for us tonight. anderson cooper starts right now. >> good evening, everyone, a lot happening tonight. two major breaking stories, a new string of tornados hammering the central plains and two potentially lethal letters. early testing pointing toward one of the deadliest toxins known to man, ricin. one sent to mayor michael bloomberg. >> right now what they know, they believe both of the letters were sent by the same person. the postmark was the same, they contained the same kind of substance, and they also both threatened mayor michael bloomberg for his positions on the gun -- on guns, specifically those illegal guns. the mayor reacted just a short time ago.