What do we know about the Tsarnaev brothers?

Tamerlan Tsarnaev, 26, loved to box. And he was talented. At 196 pounds, he represented New England as a heavyweight in the National Golden Gloves boxing tournament. He wanted to make it on an Olympic team.

His brother, Dzhokar, 19, graduated in 2011 from Cambridge Rindge & Latin School, the alma mater of actors Matt Damon and Ben Affleck. The city awarded Dzhokar a $2,500 scholarship. And he, too, was an athlete -- a wrestler. He was named student athlete of the month and made the state playoffs.

But something went wrong somewhere.

This week, the brothers Tsarnaev became the target of a massive manhunt after police identified them as the suspects behind Monday's Boston Marathon bombings.

Tamerlan died early Friday after a night of ferocious gun battles. The world watched live on television Friday night as police laid siege to Watertown, Massachusetts, and finally captured Dzhokar.

It was unclear what might have motivated the brothers to commit the heinous crime they are suspected of carrying out. All day Friday, reporters sought out people who knew them, trying to understand one thing: Why?

What unfolded was a story typical of the American immigrant narrative: A family originally from the Russian republic of Chechnya fled the brutal wars in their homeland in the 1990s. They moved to neighboring Russian republics before at last arriving in the United States.

The youngest, Dzhokar, came first with his parents, according to his aunt, Maret Tsarnaev. The older son, Tamerlan, was initially left behind with his two sisters.

Eventually, they were reunited -- a family of six whose American journey contained elements of a struggle to fit in and success in making a new life.

Another familiar narrative also emerged Friday: a high-profile crime followed by a crusade to find out who did it. First, there were photographs, then names attached to the images. And shock.

Friends and acquaintances of the Tsarnaev brothers expressed disbelief. The two men were nice, friendly. Quiet. The kind of guys you'd never even notice or look at twice if you passed them on the street.

Their aunt spoke with Canada's CTV and described the boys' childhood as perfect. Their father, Anzor, was a loving, soft-hearted man. She said he and his wife, Zubeidat, have moved back to Dagestan, which borders Chechnya.

Dzhokar came to America on July 1, 2002, as a tourist and asked for asylum, a federal official told CNN. He was naturalized as a U.S. citizen on September 11 last year.

There was some dispute over when his older brother arrived. The U.S. official said he came four years later on September 6, 2006, and held a permanent resident visa. But another federal official said Tamerlan first entered the United States on July 19, 2003.

Alyssa Lindley Kilzer said she often visited the apartment at 410 Norfolk St. in Cambridge, where the Tsarnaevs lived. Kilzer used to get facials from Zubeidat at a local spa but, after she was fired, Kilzer began going to her house.

She wrote about her experience on her Tumblr blog and said the staircase was crowded with shoes and the house was filled with the noise of arguments, cooking and other household chores. It was hardly spa-like but Kilzer thought Zubeidat gave great facials.

But she became increasingly uncomfortable going to the apartment because of Zubeidat's growing religious fervor.

"She started quoting conspiracy theories, telling me that she thought 9-11 was purposefully created by the American government to make America hate Muslims," she wrote.

Zubeidat told her: "It's real. My son knows all about it. You can read it on the Internet."

Kilzer said she met Tamerlan only once -- he wasn't friendly, she thought.

He was a dapper dresser and drove a Mercedes, according to an online photo gallery titled "Will Box for Passport."

"I'm dressed European style," Tamarlan said in a caption accompanying a photo of white leather shoes.

Photographer Johannes Hirn shot images of Tamerlan at the Wai Kru Mixed Martial Arts Center on Brighton Street in Cambridge. That's where he trained before the Golden Gloves.

He was a good boxer, said Gene McCarthy from the Sommerville Boxing Club, who'd coached Tamerlan since he was 16.

He was more than 6-feet tall, with long arms and determination written all over him. Once, he fought in a New England championship match even though he had the flu and fever blisters covered his lips. He won.

Tamerlan had been boxing since he was a kid -- his father began training him while they were still living in the Caucusus.

His younger brother started coming to the gym from the time he was 10, McCarthy said. Dzhokar followed Tamerlan around like a puppy. He'd be just behind him, doing calisthenics.

Tamerlan told Hirn, the photographer, that he gave up drinking alcohol and smoking in accordance with Muslim values. His aunt said he had become more devout a few years ago and started praying five times a day.

His mother told Russian TV channel RT that her oldest son embraced Islam but never spoke of anything extreme; never said he was on the side of jihad. Her son, she said, would never keep secrets from her. She would've known had he been involved in unsavory activities.

However, she said the FBI was checking on him, following his moves on the Internet.

"How could this happen? They were controlling every step of him, now they are saying this is a terrorist act," she said Friday.

FBI agents interviewed Tamerlan two years ago and looked at his travel history, checked databases and searched Web postings, but found no connection with terrorist groups, an FBI official told CNN.

Tamerlan traveled to Sheremetyevo, Russia, in January 2012, according to travel records provided by a U.S. official. He returned six months later, those documents show.

A YouTube page in his name had links to Islamic websites, videos from a radical Australian preacher and rap music.

He had quit college, gotten married and had a daughter two years ago, said his aunt and father.

In an interview Friday with the Russian national TV network Zvezda in Dagestan, Anzor Tsarnaev said his sons had been framed. He said he had been trying to call Dzhokar but his phone is switched off. He'd spoken with Tamerlan the day before. He wanted to make sure Tamerlan was taking care of his brother; that he was studying hard.

This was Anzor's belief: that if his sons did not get an education, they would be left to toiling their entire lives.

But there were hints that all did not sit well for Tamerlan in his new country.

He said this during the photo shoot with Hirn: "I don't have a single American friend. I don't understand them."

And in 2009, Tamerlan, then 22, was arrested for domestic assault and battery after allegedly assaulting his girlfriend, according to Cambridge Police records cited by the website spotcrime.com.

Dzhokar's friends included Torrie Martinez, 20.

Friday, Martinez stood on Cambridge Street looking down Norfolk Street, where the Tsarnaev brothers made their home. Martinez used to catch the city bus with Dzhokar every day to school and was on the wrestling team with him.

"I wish I could say he was a bad kid," said Martinez, still trying to absorb the news. "But he was a nice kid from what I knew of him. I talked with him on a daily basis. I practiced with him."

He was a sophomore when he met Dzhokar, who was a year behind him. They talked about stuff high school boys talk about; it never got too personal. Martinez didn't know Dzhokar was Chechen.

And they talked wrestling. "He was a smaller kid, but he did well for his weight class," Martinez said.

A smile appears beneath his scruffy, unshaven face.

"Between me and him, I would pin him."

Now he wished he'd whupped him a little harder. The smile vanishes from Martinez's face.

"I cried ... when they named him."

It will be hard to trust anyone again.

Larry Aaronson, a former teacher at Cambridge Rindge and Latin, said he had taken pictures of Dzhokar wrestling.

"There is nothing in his character, in his deportment, in his demeanor that would suggest anything remotely capable of any of these things that he is now suspected of doing," Aaronson said.

"He was so grateful to be here, he was so grateful to be at the school," he said. "He was compassionate, he was caring, he was jovial."

He described Dzhokar, whom he saw in the neighborhood nestled between Harvard and MIT a few weeks ago, as "a lovely, lovely kid."

Construction worker Joey Barbaso, 50, has lived in the neighborhood since he was 5. His pants are worn from hard work and stained from years of paint. That's the kind of people who live here -- along with college students.

"It's just, I dunno," he said. "You never know who you're living next to."

Robin Young, host of radio's "Here and Now," said Dzhokar was her nephew's best friend. She called him a beautiful boy.

But now he was a man despised by many.

Dzhokar had been more public about his life than his brother. More people have stepped forward with accounts of their relationships with him than about Tamerlan.

Dzhokar had a page on the Russian equivalent of Facebook on which he described his worldview as Islam.

Active on Twitter. "Ain't no love in the heart of the city. Stay safe people," he tweeted just hours after the bombings.

Tuesday, he called "fake" a story about a woman who died in Monday's bombings and was found by her boyfriend who was planning to propose.

His friend, Giovanni, who wanted only his first name used, said Dzhokar was even joking on Twitter about "how he had like a dream about eating a cheeseburger and then he was like, 'And the next day, what did I have next?'

"And I responded (on Twitter) in a joking way, 'A hot dog?'

"And here I am, like, having a conversation with this guy not knowing what he was doing or what he did."

Giovanni said he played video games with Dzhokar, but hadn't seen him in person since January. He said his friend had told him he was engaged to be married, even showing him a photo of his supposed fiancée on his phone.

"He was always just quiet, quiet in a nice (way)," Giovanni said. "You just wouldn't suspect that he'd do something so messed up."

And he said Dzhokar was particular about his identity.

"He used to tell us he's the only Chechen ... we'd ever come across," Giovanni said. "Sometimes they'd call him Russian and he'd always correct me."

He said he didn't know much about Tamerlan; only that Dzhokar had said his older brother was a boxer.

"A year ago when I met him ... to think. I had no idea I'd be friending such a messed up person. You just think, 'Oh, he seems nice, he seems innocent.'"

Dzhokar worked for a time as a lifeguard at a pool at Harvard University, said George McMasters, who hired him about 2½ years ago.

McMasters was impressed with Dzhokar's work ethic.

"He showed up on time, he watched the water, he rotated from position to position fine, got along well with others."

"He seemed like a very quiet, unassuming young man," McMasters said. "It is very surprising and shocking to see the destruction that he has brought to the city."

Last year, McMasters was deployed to Afghanistan with the Army National Guard and, when he returned to the pool job in August, Dhzokar was no longer on the staff or the schedule, he said.

Not everyone had good things to say. The harshest comments Friday came from the brothers' uncle.

Ruslan Tsarni told reporters outside his home in Montgomery County, Maryland, that he had not seen the Tsarnaev family since December 2005 and last spoke with them in 2009.

Asked what might have motivated the people who did the attack, he said: "Being losers; hatred to those who were able to settle themselves. These are the only reasons I can imagine."

Though the family is Muslim, their religion played no role in the attacks, the uncle insisted.

"Anything else to do with religion, with Islam, it's a fraud, it's a fake," he said.

He described the family as peace-loving, ethnic Chechens.

"Somebody radicalized them, but it's not my brother, who just moved back to Russia, who spent his life bringing bread to their table, fixing cars," he said. "My family had nothing to do with that family. Of course, we're ashamed, yes, we're ashamed they're children of my brother."

Tsarni said he noticed changes in the religious views of Tamerlan Tsarnaev as far back as 2009. He recalled a 2009 phone conversation where in response to some life advice he had given, Tsarnaev called him an "infidel." The young man also told his uncle he was not concerned about work or studies because God had a plan for him.

The Brothers Tsarnaev, said Tsarni, had brought shame on the Chechen people.