"JAN. 8, 2011 Jared L. Loughner, 22, killed six people with a Glock handgun in a supermarket parking lot in Tucson, Ariz., at an event for Gabrielle Giffords, who was a Democratic representative from Arizona. 2007 Mr. Loughner was arrested for possession of drug paraphernalia, but the charges were dropped. The next year, he failed a drug test when trying to enlist in the Army. Neither incident barred him from buying a gun. OCT. 2010 He was forced to withdraw from community college because of campus officials’ fears about the safety of the staff and students, his parents later said. The incident would not have shown up on a background check. NOV. 30, 2010 He passed a background check and bought the handgun at a store in Tucson, Ariz. JAN. 8, 2011 He killed six people in Tucson."