Jared Lee Loughner was turned away at one Walmart location when he tried to buy bullets just hours before his shooting rampage in Tucson. He eventually went to another Walmart and successfully bought ammunition, according to sources close to the matter who spoke to The Wall Street Journal. No reason was given for the first Walmart rejecting him. Investigators are trying to piece together Loughner's steps before he killed six people and injured 18 at a Safeway grocery store during a public event held by Rep. Gabrielle Giffords. Officials are also examining surveillance footage showing the 22-year-old shooter standing in line, behind U.S. District Judge John Roll, waiting to talk to Giffords. Roll was later killed in the gunfire. Loughner, who was recognized as mentally unstable, is charged with two counts of murder, two counts of attempted murder, and one count of attempting to assassinate a member of Congress.