AFP - Getty Images, file Jared Loughner, 24.

Jared Loughner hadn't been the same since he got fired from a job at a mall in Tucson, his parents said. He had been expelled from college. After a visit from campus police, his parents decided to hide a shotgun that Loughner owned in the trunk of their car in the garage so he didn't have access to it in the house.

A slew of details about Loughner, 24 -- who has pleaded guilty to killing six people and wounding former Rep. Gabrielle Giffords and a dozen others in a Jan. 8, 2011, shooting spree in Tucson -- emerged as authorities investigating the rampage released more than 2,700 pages of documents that they have compiled.

Among the thousands of interviews, police reports and survivors' statements released Wednesday, one theme was constant about Loughner, who has since been diagnosed with schizophrenia: As his father, Randy Loughner, told investigators at the time, he "just doesn't seem right lately."

Loughner was fired more than a year before the shooting, his father told investigators after the shooting, according to the documents. Trying to have a rational conversation with his son became more and more difficult after that, he said.

"Lost, lost and just didn't want to communicate with me," Randy Loughner said.

After Loughner was expelled, things got worse: Randy Loughner said his son felt harassed by campus police, who came to the Loughner home and asked if there were any firearms in the house. Loughner had bought a 12-gauge shotgun in 2008; at the recommendation of Pima Community College campus police, who recommended any firearms be taken away, they hid the shotgun and an antique weapon they owned.

"He had a shotgun. And I took it away," Randy Loughner told police. "They suggested that if I had any firearms, to take them away. And I did."

A former friend of Loughner's, Zachary Osler, was an employee at a store where Loughner later purchased a Glock handgun used in the Tucson rampage. Osler described the awkward encounter he had with Loughner.

"His response is nothing. Just a mute facial expression. And just like, he, he didn't care," Osler told investigators. He said the change in Loughner's personality made him uncomfortable to be around.

"He would say he could dream and then control what he was doing while he was dreaming," Osler said, adding Loughner never mentioned Giffords in conversation to him.

Loughner's mother, Amy, felt her son's behavior was so odd that she tested him for drugs. Loughner kept a journal that was written in illegible script, his father said. Despite their concerns, Loughner's parents said they never sent him to get help and he had never been diagnosed as mentally ill.

On the morning of the shooting, Loughner's father said his son had been "acting strange." Loughner had taken his father's car early in the morning, returned home briefly, left again, then returned home once more before leaving on foot with a backpack.

Pima County Sheriff's Deputy T. Audetat Jr. wrote in his police report that when he arrived at the scene, he saw a man being held down by "two or three people". He handcuffed the shooter; in the shooter's pocket, in addition to two Glock magazines, fully loaded, he found a folding knife and a credit card and ID card, he said.

He described what the shooter was wearing: black beanie, black hooded sweatshirt, khaki pants. Another deputy noticed he was wearing earplugs, he wrote in his report.

One of the victims of the shooting outside the Safeway supermarket, Ronald Barber, told police of the rampage, "I was laying on my right side and I could see the blood coming out. You know, and, uh, and all I remember is seeing the congresswoman with her back to me, on her side. On her right side, uh, with her head up against the window, you know, of the Safeway. And Daniel, um, who is our intern, saying, 'Stay with me, congresswoman, stay with me.'"

Once in the patrol car, Loughner pleaded the Fifth Amendment repeatedly, Deputy Audetat wrote. At the police station, Loughner said very little besides, "I just want you to know that I'm the only person that knew about this," according to the deputy.

In his four-hour interview with authorities following the morning rampage, Loughner sat in restraints and was polite and cooperative with authorities, documents show. He asked to use the restroom at one point, saying thank you when he was permitted to. Although after a while he complained, "I'm about ready to fall over."

Loughner will spend the rest of his life behind bars but is not eligible for the death penalty because of his plea deal in the case. Giffords retired from her position in Congress a year after the shooting to focus on her recovery.