For a time, Jared Loughner appeared to be no more than a troubled teenager, the kind that causes heartache for parents but doesn't make headlines. He got drunk at school, smoked pot regularly and sent friends strange stories he had written.
Soon, though, there were signs he was sliding toward something far darker. By this past spring, his odd outbursts and twisted ramblings had begun frightening his classmates and alarming his professors. One teacher later described him as "someone whose brains were scrambled."
Days after Mr. Loughner, 22, shot Congresswoman Gabrielle Giffords in the head and killed six others at a strip mall in Tucson, he has provided no explanation for the rampage. Trying to find one leads to the pathways of an increasingly disturbed and paranoid mind.
On Monday, wearing a tan prison uniform, he appeared before a Federal Court judge in Phoenix. He briefly answered procedural questions, responding in the affirmative when asked whether he understood his legal rights. In a mug shot, he stares straight at the camera and smiles.
Mr. Loughner spent his adolescence in Tucson, living in a modest home with his father and mother, a long-time city government employee. Neighbours describe them as a solitary family not prone to friendly chitchat. Mr. Loughner was often seen walking his dog while plugged in to an iPod.
His connection to Ms. Giffords, however tenuous, dates back to the summer of 2007 when he attended an outreach event similar to the one on Saturday. He told friends that he had asked Ms. Giffords a question about the meaning of language and was irritated by her lack of response. Ms. Giffords was "stupid and unintelligent," he reportedly told a classmate.
Tracking what happened to Mr. Loughner in the intervening three years seems to reveal a young man growing more and more unstable. Months after the event with Ms. Giffords, he had a run-in with police for possessing drug paraphernalia. A year later, he was cited for writing graffiti on a street sign. He tried to enlist in the army, but was rejected because of his drug use.
Mr. Loughner became more eccentric. At Pima Community College, where he was a student, his classroom behaviour veered toward the bizarre - shouting out non-sequiturs and writing odd things on quizzes ("MAYHEM FEST").
In one class, after a teary-eyed young woman read a poem about abortion, Mr. Loughner burst out laughing and said, "Wow, she's just like a terrorist, she killed a baby," a fellow student told The Washington Post.
Another student, a middle-aged woman who had returned to college, was in an algebra class with Mr. Loughner last June and described him at the time to friends in chilling terms.
"We have a mentally unstable person in the class that scares the living crap out of me," she wrote in an e-mail provided to U.S. newspapers. "He is one of those whose picture you see on the news, after he has come into class with an automatic weapon. Everyone interviewed would say, 'Yeah, he was in my math class and he was really weird.' "
Campus police talked to Mr. Loughner five times between February and September about his disruptive behaviour in classes and in the library. After the college found a YouTube video where Mr. Loughner described the institution as "unconstitutional," it suspended him. In a letter delivered to his parents, the school said he could return only after a mental-health professional had evaluated him and determined he posed no threat.
Mr. Loughner's politics appear to have been a strange brew of conspiracy theory, anti-government paranoia and atheism. In his YouTube videos, Mr. Loughner displayed a warped logic all his own, crafting strange "if …thus" propositions that appear on the screen with a thumping music beat in the background.
"The government is implying mind control and brainwash on the people by controlling grammar," the text in one video reads. It continues, "No! I won't pay debt with a currency that's not backed by gold and silver. No! I won't trust in God."
Mr. Loughner's views bear a resemblance to those espoused by conspiracy theorists such as David Wynn Miller and American Renaissance, a white supremacist magazine, The New York Times reported. But it does not appear now that Mr. Loughner had any contacts with such groups, reinforcing the picture of him as a disturbed loner.
His favourite books, compiled on a Myspace page apparently belonging to him, show no consistent philosophy - they include Mein Kampf, Animal Farm, The Communist Manifesto, and Alice in Wonderland.
In late November, Mr. Loughner went to a Sportman's Warehouse store in Tucson, where an employee performed an instant background check and sold him a Glock 19 semi-automatic handgun.
Just hours before Saturday's shooting, he posted what appeared to be a farewell message on his Myspace page. "Goodbye … Dear friends …Please don't be mad at me … I cannot rest."
(Editor's note: The mother of Jared Loughner is a long-time Tucson city government employee, not his father, as stated in an earlier version of this story. This online version has been corrected.)