CNN) -- The suspect in the weekend massacre in Arizona scrawled "my assassination" and "I planned ahead" on an envelope found in his home, according to court documents released Sunday. The details were part of criminal complaint filed against 22-year-old Jared Lee Loughner, the Tucson man now charged in Saturday's bloodbath at a supermarket where U.S. Rep. Gabrielle Giffords was hosting an open house for constituents. Investigators found a letter from the congresswoman in a safe at the house where Loughner lived with his parents, thanking him for attending a similar 2007 event, a federal agent's affidavit states. "Also recovered...