Reporting from Los Angeles and Tucson —
The two teenagers were in an old minivan just before midnight, driving through their scrubby neighborhood on the outskirts of Tucson when they were pulled over by sheriff's deputies. The driver and his passenger, Jared Lee Loughner, both smelled strongly of pot. It was the eve of Loughner's 19th birthday. Deputies cited him for possessing drug paraphernalia, his first criminal charge as an adult.

Between that stop Sept. 9, 2007, and Jan. 8 of this year — the day he was arrested as a suspect in shootings that killed six and wounded 13, including U.S. Rep. Gabrielle Giffords, outside a Safeway store in Tucson — Loughner frequently acted and sounded like a young man in need of mental health intervention.

He'd been kicked out of school, was rejected by the Army and struggled to find work. He was fired from a volunteer job at an animal shelter. His Internet postings were hostile and incoherent, with certain themes repeated — a distrust of government and his college, the Constitution, illiteracy and "lucid dreaming." He alienated fellow players in an online game with disjointed, hostile posts, including one in which he called the physicist Stephen Hawking a "freaking retard" and equated rape with sex.

Interviews with friends, teachers and classmates, and reviews of school documents and law enforcement reports — plus Loughner's own writings and comments — depict a young man's downward spiral, slow at first, accelerating dramatically a year ago, and culminating with his arrest on suspicion of murder eight days ago.

With so many danger signs, so many people having taken note of his deteriorating state, the haunting question for authorities and those close to Loughner is whether something could have been done to head off the tragedy. The record shows that attempts to intervene focused on his behavior, not on what caused it. As far as is known, Loughner never received professional help.

More than three years ago, those who knew him began to notice unsettling changes.

In August 2007, Loughner had shown up at a Giffords event and asked her a question. He told George Osler, the father of a childhood friend, that he was not satisfied with his congresswoman's response.

"He thought that she was fake," Osler said.

An old friend, Bryce Tierney, recently told Mother Jones magazine what Loughner had asked: "What is government if words have no meaning?"

Michelle Montanaro, a second-grade teacher and mother of Jared's onetime best friend Alex Montanaro, said that during a 2007 visit to their home, Loughner spoke excitedly about becoming a writer and told an indecipherable story about an angel talking to a reporter after the end of the world. "I didn't really understand it," Montanaro said. "Neither did Alex. We just sort of looked at each other."

Loughner, an only child, was born Sept. 10, 1988. His mother, Amy, in her early 50s, is a manager at Agua Caliente Park on the east side of Tucson. His father, Randy, 58, used to work as a carpet layer and pool surfacer, but has not worked recently, neighbors said. The Loughners' 1,400-square-foot brick home, landscaped with mesquite and saguaro cactus, was purchased in 1977 and has a county-assessed value of $105,000.

The Loughners are very private, neighbors said.

"They're like a mountain man. They want to be alone," said neighbor Wayne Smith, who broke the news of their son's arrest to the couple.

At Tortolita Middle School, Loughner was a normal boy whose passions reflected the times, friends said.

"He'd be at every popular block party," said Lela Chavis, 22, who bonded with him over music in their choir class. He was a considerate friend who would call her about class work if she missed school, she said.

Loughner was a talented tenor saxophone player with a taste for jazz, but he also liked the punk bands Rancid and the Misfits, and played in a garage band, friends said.

His favorite books, listed on his MySpace page, include classics such as "Animal Farm," "Brave New World" and "To Kill a Mockingbird," and political tracts such as "Mein Kampf" and "The Communist Manifesto."

An eighth-grade photo shows Loughner with bangs and small, roundish, wire-rimmed glasses. That prompted some classmates to call him Harry Potter, and once someone taped a "kick me" sign on his back, according to the Washington Post.

At Mountain View High School, Loughner was "very sweet, caring and kind, had no interest in drugs or alcohol, and had a big interest in music," said his girlfriend at the time, Kelsey Hawkes, now a junior at the University of Arizona. "He didn't start acting differently until after we had been broken up."

When he was 16, Loughner was the victim of a nasty prank in the school cafeteria. Another student poked him in the upper arm with a weapon fashioned from a plastic ballpoint pen and a needle. Loughner became dizzy and pale. Unable to stand, he had to be helped to the nurse's office. He did not press charges.

In spring 2006, at 17, Loughner arrived at school one morning seriously intoxicated, and was taken to a hospital. He told sheriff's deputies he had consumed about 12 ounces of vodka that he stole from his father after his father yelled at him.

Some of Loughner's friends have said his parents doted on their boy; others said he fought with his father, who sometimes had a temper.

The year 2008 was fraught with failures and setbacks. Loughner's college transcript shows no coursework that fall.

Osler, whose son Zachary was close to Loughner then, said Loughner used pot and the legal hallucinogen salvia. Zachary told his father that Loughner kept pot and vodka in a safe at home.

Osler worried Loughner was "living in a fantasy world." But he never suggested that Loughner seek help because he did not seem seriously disturbed, Osler said.

Loughner's parents were aware of their son's growing troubles, Osler believed: "They did know there were problems — the drugs, the alcohol use, the incessant talking about … what's real and not real."

The Loughners showed up at Osler's house one morning looking for their son, fearing he had run away. Zachary told them Loughner was at a nearby motel. Osler dismissed the incident as a "normal family squabble."

"They were concerned for his well-being, like any parents would be," Osler said.

People who know Loughner said he was not interested in politics. "He didn't care about elections, abortion, immigration, healthcare," Osler said.

He registered without declaring a party affiliation, and voted only twice — in the 2006 and 2008 general elections, according to the Arizona Office of the Secretary of State.

In fall 2008, Loughner reported being harassed online and also got arrested for tagging.

On Oct. 2, he walked into the Pima County Sheriff's Department to report that someone had stolen his identity to create a phony MySpace page. A report noted that Loughner was worried prospective employers would see the page "myspacedotcomscrewupretard."

Later that month, Loughner tagged a traffic sign in Marana, a town north of Tucson. He was arrested and released with a citation. He entered a diversion program and paid $500 restitution.

Toward the end of 2008, Loughner swore off cigarettes, drugs and alcohol, cut his hair and started dressing more conservatively and working out, Osler said. He wanted to be a soldier.

But the Army rejected him, a devastating blow. (The Associated Press, quoting an anonymous military official in Washington, reported that Loughner had failed a drug test, though the official did not know what drug was detected.)

"He just slowly spiraled into madness," said Osler, adding that Loughner's inappropriate grin unsettled people. "He just had so many things going bad in his life."

After that, Loughner broke off contact with Osler's son and other friends.

Loughner was enrolled at Pima Community College throughout 2009, according to his transcript. He took biology, literature and film and a course called Making Career Choices. The classroom disruptions that brought him to the attention of school police and administrators would not begin until January 2010.

On the Pima campus, Loughner became a focus of official concern. His odd behavior in an advanced poetry class sparked the first of five encounters with campus police and involved administrators.

Loughner would grin, speak gibberish, laugh to himself and clench his fists, said Steven Cates, 21, one of three poetry students who said they feared Loughner would bring a gun to school.

Amy Jensen, 26, said she dropped the class because Loughner created a "chemistry of uneasiness.... He just creeped me out." She said she pictured him with a gun.

Cates said he tried to strike up conversations with Loughner when he'd see him on campus. He said he had a gut feeling about Loughner: "If something did happen, maybe I wouldn't be on his list of targets."

In late January 2010, Loughner's response to a poem about a woman's abortion was so off the wall that campus police and administrators were brought in.

"I remember him saying something about strapping a bomb to the fetus and making a baby bomb out of it," said classmate Lydian Ali, 26.

Pima College administrator Aubrey Conover met with Loughner and his mother. "He said that the class had been talking about abortion, which made him think of death, which made him think of suicide bombers, which made him think of babies as suicide bombers," Conover wrote in a report.

To avoid ejection, Conover said, "Jared said he would just not say anything in class."

In March 2010, according to the Arizona Republic, Loughner was fired from a volunteer dog walking position with the Pima Animal Care Center after defying instructions and walking puppies into a parvovirus quarantine area.

On April 6, Pima campus police were called to the library, where Loughner was making loud noises while working on a computer and listening to music with ear buds. He was told his behavior was unacceptable, the police reported, and he agreed to stop.

Two weeks later, he began posting on Earth Empires, an online gaming site. (A site administrator identified Loughner as the poster "Dare"). Dare's comments were angry and disjointed; he wrote about weight lifting, rejection by women and a failure to find work because of his run-ins with law enforcement.

He wrote that he'd been fired from jobs at Peter Piper Pizza, Red Robin, Quiznos, Eddie Bauer and a Chinese fast-food restaurant.

"I had to walk out of Red Robin — terrible situation," he wrote. "Mental breakdown."

In mid-May, about the same time he was talking about his job problems online, campus police were called to his Pilates class. His instructor asked for protection after a heated discussion with Loughner over his B grade. "told this woman. That she was a Bully," he wrote on Earth Empires.

On May 18, a teammate responded: "The more I read Dare's posts, the more I think he's just drunk/high."

Loughner replied: "I have no substance abuse problems currently."

A month later, Loughner updated his job search: "Currently at 65 applications. No interview."

From the first day of a summer algebra class, the instructor and students were unsettled. "How can you deny math instead of accepting it?" he challenged the instructor, Ben McGahee.

"One lady came to me at the end of class and said, 'I'm really scared for my life,'" said McGahee, who alerted administrators.

The next day at 8:20 a.m., school counselor DeLisa Siddall pulled Loughner out of class to talk.

"He gives me this dark, evil look like, 'You're trying to single me out; you're trying to get at me,'" McGahee said.

Siddall, who recounted the conversation in an e-mail to the math department chair and others, told Loughner he had been disruptive.

"He said he paid $200 for the class, so he should have the right to speak," she wrote. He also told her that he felt "scammed" because he had taken other courses, failed them and not gotten his money back.

"This student was warned," Siddall concluded. "Since his resolution was to remain silent in class and successfully complete the course, I had no grounds to keep him out of class."

A report on the disturbance was filed June 3 with campus police.

During the second week of class, Loughner shaved his head. He continued to have outbursts, but at other times would withdraw, doodle and listen to his iPod.

On June 14, in an e-mail to a friend that was provided to the Washington Post, Loughner's classmate Lynda Sorenson wrote: "We have a mentally unstable person in the class that scares the living crap out of me. He is one of those whose picture you see on the news, after he has come into class with an automatic weapon.... I sit by the door with my purse handy."

After Loughner accused McGahee of violating his 1st Amendment rights, administrators removed him from the class.

In the fall semester, trouble began almost immediately. This time, it was during biology.

Loughner turned in an assignment late and was told by his instructor that he would receive only half credit. Loughner's reaction was so intimidating, the instructor called campus police.

"Loughner was insistent that his freedom of speech was being taken away," the Sept. 23 police report said. The officer noted that during questioning, Loughner's head "was constantly tilted to the left and his eyes were jittery and looking up to the left."

Officers escorted him to Conover's office.

That night, Loughner uploaded a video to YouTube in which he walked around campus, giggling under his breath, narrating a tour of classrooms where he claimed his rights had been infringed.

"I'm in a terrible place. This is the school that I go to. This is my genocide school" — he laughs, "heh-heh-heh" — "where I'm going to be homeless because of this school."

His camera lingers on the campus police sign. "This is the police station," Loughner said. "This is where the whole shaboozie goes down with illegal activity."

Four days later in a meeting, Loughner told Conover that he had paid illegally for his courses because "I did not pay with gold or silver." At one point, Loughner stopped talking and said his parents had told him not to say more, according to Conover's written summary. To solve the impasse, Conover asked Loughner and his parents to meet the next evening.

On Sept. 28, Loughner and his mother met with Conover and a counselor. Again, Loughner spoke little. "Jared gave a scripted answer of, 'I know I have to follow Pima processes and write what the teacher wants,'" Conover wrote.

"Throughout the meeting, Jared held himself very rigidly and smiled overtly at inappropriate times," Conover wrote. They agreed that Loughner would return to Conover's office the next week to sign a behavioral contract.

Before the meeting could occur, campus police found Loughner's "genocide school" video. They delivered a letter of suspension to him at home and had a brief conversation with Loughner's father, according to their report.

On Oct. 4, the Loughner family met with campus officials and agreed that their son would withdraw from the school. In a follow-up letter, administrators wrote that Loughner could not return unless a mental health professional certified he was not a danger to himself or others.

The next month, on Nov. 14, the staff of a local tattoo shop felt something was wrong with the customer who strolled in with a 9-millimeter bullet and paid $60 to have its likeness inked in black and gray on his right shoulder blade. He told shop employees that he liked to shoot things and that he could control his dreams.

"We were like, 'What's wrong with that guy?'" said tattoo artist Brittney Ramirez. "We were saying that maybe he could do some damage if he wanted to." A week later, Loughner returned for a second bullet tattoo.

In the months that followed, Loughner's posts on YouTube and MySpace were incoherent, paranoid and grandiose.

On Nov. 22, he produced a YouTube video stating that he was thinking about creating a new currency. On Nov. 30, he ranted at the college, claiming to be a victim of fraud. That day, he purchased the Glock authorities say was used in the Tucson shootings.

"I'm able to control every belief," he posted Dec. 6 on YouTube.

The night before the Safeway rampage, Loughner checked into a Motel 6 on Ina Road near his home, but apparently did not sleep much, if at all. He made purchases throughout the night at a Circle K, a Wal-Mart and a Walgreens.

About 2 a.m., Loughner phoned his old friend Bryce Tierney. The call came from a restricted number, Tierney said later, so he didn't pick up. Tierney repeated the message to reporters: "Hey, it's Jared. We had some good times and peace out."

A couple of hours later, Loughner wrote on MySpace, "Goodbye friends."

Moments before sunrise, he bought bullets at a Super Wal-Mart, then slowly crept through a red light in front of a state Game and Fish officer, who let him go with a warning. He drove the 1969 Chevy Nova home.

Sometime before 9:40 a.m., Loughner's father confronted his son after seeing him take a black bag out of the Nova. Loughner fled on foot while his father tried to give chase in his truck.

Loughner called a cab from the Circle K near his house and rode to the Safeway, about five miles away. He went into the store with the cabdriver to get change for the fare.

Outside, Giffords was meeting her public.

After he heard about the shooting, Tierney called 911. "The shooter was, uh, someone that I knew," said Tierney, on a tape released Friday by the Pima County Sheriff's Department. "He didn't say anything about shooting people or anything, but I guess he was trying to come into contact with me last night."

robin.abcarian@latimes.com

maeve.reston@latimes.com

molly.hennessy-fiske@latimes.com

Abcarian and Reston reported from Los Angeles, and Hennessy-Fiske from Tucson. Times staff writers Rong-Gong Lin II, Kate Linthicum and Rick Rojas in Los Angeles, and Sam Quinones, Nicole Santa Cruz, Ashley Powers and Seema Mehta in Tucson contributed to this report.