Jared Lee Loughner bought the handgun used in the Jan. 8, 2011, mass shooting about six weeks after his parents confiscated his first firearm, a shotgun, files released Wednesday by the Pima County Sheriff's Department show.
Loughner bought the Glock 19 9 mm semiautomatic handgun he used in the rampage on Nov. 30, 2010, at a Sportsman's Warehouse near his home northwest of Tucson.
When one employee at the store, at 3945 W. Costco Drive, waited on Loughner, he asked to speak to a younger staff member.
A younger employee then helped Loughner complete the purchase despite thinking the request was strange. A manager signed off on the background check forms, per company policy.
The gun plus a 15-round magazine and box of ammunition cost $559.66.
A few weeks later, Loughner went to the home of his friend Anthony Kuck and showed him the handgun he had purchased, as well as a tattoo of two bullets on his shoulder blade. Kuck asked him to leave because of it.
Kuck's roommate, Derek Heintz, who had also known Loughner for many years, saw the weapon and a 32-round clip as well. Heintz took a couple of bullets out of the magazine and Loughner gave him one to keep.
Heintz asked Loughner what he was going to do with the weapon and such a large capacity magazine. Loughner replied that he would use it for home defense.
But handwritten notes recovered in a safe in Loughner's bedroom indicate that as early as Dec. 6, 2010, he had plans to assassinate then-U.S. Rep. Gabrielle Giffords.
The notes advised the reader to keep the casings and gun lock found in the safe because they were "historic."
About 7 a.m. the morning of the attack, Loughner tried to buy more ammunition.
A clerk at Walmart, 7635 N. La Cholla Boulevard, later told deputies that Loughner was acting so erratically that he lied and said the store was out of stock.
Loughner approached the clerk walking really fast. After seeing that there was no 9 mm ammunition in the display case, he urged the clerk to look for more in the back.
Feeling uneasy about how rushed Loughner seemed, the clerk announced that he was out of stock before he even checked.
"I could tell on his face that he was really angry about it," the clerk told investigators. "He just kind o' swung away and just walked off."
Another employee who helped Loughner at the customer service desk said, "He's one of those types you don't forget." She also said he seemed rushed.
Loughner successfully purchased ammunition shortly afterward at another Walmart store, 8280 N. Cortaro Road. He spent $83 on eight boxes of bullets.
Loughner's original gun, a single-shot shotgun bought in 2008 at the same Sportsman's Warehouse, was locked, meanwhile, in the trunk of a yellow car in his family's garage.
His parents had taken it away from Loughner after his expulsion from Pima Community College. Administrators there recommended that any firearms be taken away. The gun was locked away with another family firearm.
Compiled by Carli Brosseau, Stephanie Innes, Kimberly Matas, Becky Pallack, Kim Smith and Tim Steller.