When deputies arrested Jared Lee Loughner Saturday morning they found a four-inch buck knife, a plastic bag with currency, two 15-round magazines, a bank card, and his Arizona driver’s license inside his pockets, officials said Friday.

Thursday morning a black bag containing ammunition found by a teen on the northwest side was linked to Loughner, the man facing charges in connection with a shooting spree that left six dead and 13 wounded, officials say.

An 18-year-old man walking his dog near Loughner's home found the bag in a wash Thursday morning. He took it to a neighbor's house and called police, said Deputy Jason Ogan, a Pima County Sheriff's Department spokesman.

Deputies went to the 4000 block of West Soledad Place, where they inspected the black diaper bag, which resembled a backpack, and believe it is the bag Loughner took with him Saturday morning before the mass-shooting outside a Safeway, Ogan said.

Investigators found 9 mm ammunition inside the bag, Ogan said. Deputies gave the bag to the FBI for further analysis, he said.

Loughner's father, Randy Loughner, told investigators earlier this week that he found his son near the front of the house Saturday morning removing a black bag from the family's vehicle. He had concerns about what his son was doing and about what he had in the bag, sheriff's Bureau Chief Rick Kastigar has said.

"The father asked him something along the lines of 'What are you doing?' or 'What's in the bag?' " Kastigar said Wednesday.

Loughner mumbled a reply and quickly walked away, Kastigar said.

The father got in his vehicle and looked for his son but was unable to find Loughner.

Jared Loughner later took a cab to the Safeway near North Oracle and West Ina roads, where officials say he opened fire on people at an event put on by U.S. Rep. Gabrielle Giffords, who is recovering from a gunshot to the head.

Loughner was charged Sunday in the killing of U.S. District Court Chief Judge John Roll, 63, and Gabe Zimmerman, 30, a Giffords staff member, and with the attempted murder of Giffords and two other members of her staff, Pamela Simon and Ron Barber.

Giffords is in critical condition at University Medical Center, where Simon and Barber also are recovering, doctors said.

On StarNet: Listen to audio of the sheriff's radio traffic for the first few minutes after the shootings at azstarnet.com/multimedia