Two U.S. officials say Dzhokhar Tsarnaev, the surviving suspect [in the Boston Marathon bombings], was unarmed when police captured him hiding inside a boat in a neighborhood back yard. Authorities originally said they had exchanged gunfire with Dzhokhar for more than one hour Friday evening before they were able to subdue him. The officials tell The Associated Press that no gun was found in the boat. Boston Police Commissioner Ed Davis said earlier that shots were fired from inside the boat. Investigators also believe the brothers helped finance their plot through drug sales. Sources say Tamerlan Tsarnaev, who was unemployed, made money selling marijuana. Police think the brothers killed a Massachusetts Institute of Technology campus police officer for his weapon while they were the subjects of last week's massive manhunt. The brothers only had one real gun and one pellet gun when they were on the run Thursday. Investigators now believe that Officer Sean Collier was killed Thursday because the two bombing suspects wanted to take his gun. Investigators believe because the officer's holster had a locking system, they apparently couldn't get the gun out. Collier was shot in the head execution-style while sitting in his patrol car. In his questioning in the hospital, Dzhokhar Tsarnaev said they were self-taught and self-radicalized.