The FBI released the documents in response to media requests for investigative files associated with the Jan. 8, 2011, shooting that killed six people and injured 13, including Giffords. Jared Loughner, 25, was sentenced to life in prison for the shooting outside a grocery store in Tucson.
Loughner's deteriorating mental state before the shooting has been chronicled in previously released documents, psychological reports and media interviews with witnesses, but the FBI files released Thursday provide some new details.
Loughner ranted on his MySpace page about the government spending illegal money, how he couldn't trust the police and referred several times to suicide and killing authorities. On Dec. 20, 2010, he wrote: "I HAVE THIS HUGE GOAL AT THE END OF MY LIFE: 165 rounds fired in a minute!"
A week earlier, according to the FBI files, Loughner wrote that he was glad he hadn't committed suicide.
"I'll see you on National T.v.! This is a foreshadow...why doesn't anyone talk to me?" Loughner wrote.
In another online post about a month before the shooting, Loughner wrote about strange dreams he was having.
"There are important figures in my dreams that accomplished political aspirations: Hitler, Hillary Clinton and Giffords to name a few," he wrote.
One report indicates that a witness called the FBI the day after the shooting to tell authorities that Loughner had often been seen at a city library watching videos and that he "would repeatedly talk loudly to the computer causing a disturbance to others in the area."
The witness told authorities they remembered "looking over to his computer and noticing he was watching Giffords speeches online."
One FBI file dated the day of the shooting says an agent interviewed a woman who once worked with Loughner at a store.
"She advised that Loughner would talk about zombies, guns and things that she and the other employees could not relate to," according to the documents.
In another file, the FBI said Loughner approached then-Giffords aide Ron Barber before the shooting.
"Where is the congresswoman?" the FBI wrote Loughner asked Barber, who was also shot in the attack.
A few minutes later, Loughner emptied a 30-round magazine as he fired into the crowd.
A spokesman for Barber, who later succeeded Giffords as the representative in the southern Arizona district, said the FBI report was inaccurate.
"One of our interns was approached by Loughner. Ron Barber never talked to Loughner, before or after the shooting," spokesman Mark Kimble said Thursday night.
On the morning of the shooting before the attack, Loughner was pulled over by an Arizona Game and Fish law enforcement officer for running a red light, according to the files.
The officer said Loughner was "calm but nervous."
When Loughner was told he wouldn't be getting a ticket, he began crying.
"Loughner composed himself and said he was headed to his home and that he did not live far away," according to the files.
In another section of the FBI records, authorities noted an interview with a woman who claimed to be a psychic.
She said Loughner sought out her services in 2005 and that he frightened her, telling the woman, "I hear voices and they tell me to do things."
The FBI records also indicate that Loughner may have met Giffords while he was in high school several years before the shooting. One person interviewed by agents said Giffords came to the school to talk to students, and that Loughner asked her, "If words could not be understood, then what does government mean?"
"Giffords could not answer the question the way Loughner liked, and it blew his mind that she not could not answer his question," the FBI wrote, according to the witness.
Loughner also argued with instructors and disrupted classes at Pima Community College, leaving one instructor intimidated. A witness told the FBI that Loughner once had a strange reaction to another student's poem, saying it was about abortion, wars and killing people. "He said, 'Why don't we just strap bombs to babies,'" according to the FBI files.