"Paul Ciancia, the gunman whose 2013 rampage at Los Angeles International Airport left a Transportation Security Administration officer dead and three others injured, has agreed to plead guilty to all pending federal charges, according to court papers filed Thursday.... Ciancia, who had been living in Los Angeles for about 18 months before the shooting rampage, had purchased the Smith & Wesson semiautomatic rifle nearly seven months before he stormed into the terminal.... "I'm so sorry that I have to leave you pre-maturely, but it is for the greater good of humanity. This was the purpose I was brought here," he told his brother. To his sister, Ciancia wrote that he had to "stand up to these tyrants." He asked his sister not to let the media distort his actions. "There wasn't a terrorist attack on Nov 1. There was a pissed off patriot trying to water the tree of liberty," he wrote."