Timeline: A look at Tamerlan Tsarnaev's past

Boston Marathon bombing suspect Tamerlan Tsarnaev, 26, died early Friday after a gunfight with police. Investigators are looking into his past for clues about last week's terror attack. Here's a look at some key dates, compiled from CNN's reporting and other media reports.

Tamerlan Tsarnaev is born. His uncle, Ruslan Tsarni, says Tsarnaev was born into an ethnically Chechen family in Kyrgyzstan.

The Tsarnaev family moves from Tokmok, Kyrgyzstan, to Dagestan, according to the state committee for national security of the Kyrgyzstan government.

"They lived here for a year, not the whole year. They arrived at the school in 2001 and departed in March 2002," a spokesman at a school the children attended in Makhachkala, Dagestan, told Russia Today, a Russian state-funded television network.

Parents Anzor Tsarnaev and Zubeidat Tsarnaeva immigrate to the United States with their son, Dzhokhar. Their three other children -- Tamerlan Tsarnaev and two sisters -- stay behind in Kazakhstan with an uncle, his aunt told reporters in Canada this week.

Tsarnaev, then 16, is in Turkey in July 2003 for 10 days on a Kyrgyz passport, a senior Turkish official says.

He comes to the United States that month, along with his two sisters, his aunt, Maret Tsarnaeva, told the Toronto Sun.

Tamerlan Tsarnaev first enters the United States through New York's JFK International Airport, a federal official says.

Tsarnaev is registered to fight with USA Boxing, the organization that oversees amateur boxing in the United States, a spokeswoman says. Tsarnaev delivered pizza and held other jobs while boxing, his aunt said.

In an interview with the Lowell Sun newspaper in Massachusetts, after winning a fight in a local boxing tournament, Tsarnaev says he grew up in Grozny, Chechnya, and moved with his family to the United States in 2003 in hopes of starting a new life. "I like the USA ... America has a lot of jobs. That's something Russia doesn't have. You have a chance to make money here if you are willing to work," he said at the time, according to the Sun. He also told the newspaper that he studied music at a school in Russia and played the piano and violin.

Tsarnaev attends Bunker Hill Community College as a part-time student, a school spokeswoman says.

Tsarnaev "got involved in religion," according to his mother. "Started following his own religion, never told me he could be on (the) side of jihad," Zubeidat Tsarnaeva told Russia Today.

Tsarnaev is photographed training at Wai Kru Mixed Martial Arts in Boston for a university magazine story. The caption of one photo in a gallery describes Tsarnaev as a native of Chechnya and says he has been in the United States for five years. A quote attributed to Tsarnaev says, "I don't have one American friend. I don't understand them."

That same year, Tsarni says, he had a falling out with Tamerlan. "I got into really a state of shock from changes I heard, I wouldn't say I saw, I heard from Tamerlan," he told CNN. He recalled a 2009 phone conversation in which 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. According to his uncle, Tamerlan Tsarnaev's radicalization started in not in Chechnya, but in Cambridge, Massachusetts, at a local mosque.

Tsarnaev competes at 201 pounds in the 2009 Golden Gloves Tournament of Champions in Salt Lake City, losing in the first bout.

Tsarnaev is arrested, accused of domestic abuse and battery after allegedly assaulting his girlfriend, according to Cambridge Police Department records.

Tsarnaev wins a local heavyweight boxing title. "He said he'd gotten married and had a little baby. He was a very nice guy," said Gene McCarthy of the Somerville Boxing Club in Massachusetts. "I brought him to the registration, and while he was waiting in line, he saw a piano and was playing classical music like it was Symphony Hall."

Tsarnaev and Katherine Russell are issued a marriage license by the city clerk in Cambridge, Massachusetts. An attorney for Russell's family, Amato DeLuca, told CNN that the couple have a 2-year-old daughter, whom Tsarnaev cared for while Russell worked long hours as a home health aide.

Tsarnaev begins praying five times a day, his aunt told reporters.

Russia asks the FBI to look at Tsarnaev's activities, a senior U.S. official said.

"The request stated that it was based on information that he was a follower of radical Islam and a strong believer, and that he had changed drastically since 2010 as he prepared to leave the United States for travel to the country's region to join unspecified underground groups," the FBI said in a statement.

After interviewing Tsarnaev and family members, the FBI says it "did not find any terrorism activity, domestic or foreign, and those results were provided to the foreign government."

Tsarnaev leaves New York for Russia. It's not clear what he did while in Russia, but Tsarnaev's father has said his son was with him at all times.

Officials have said they're worried about what might have happened on the trip.

"What I'm very concerned about is that when he went over there, he very well may have been radicalized and trained by these Chechen rebels, who are the fiercest jihad warriors," said Rep. Michael McCaul, a Republican from Texas who is chairman of the House Homeland Security Committee.

Tsarnaev returns to the United States, arriving at JFK Airport in New York. Travel documents show a photo of him with a beard, according to a U.S. official who declined to be named because of the sensitivity of the issue.

It is unclear whether Tsarnaev made other trips to Russia. On Sunday, McCaul said he thought it was likely Tsarnaev made other trips to the region. "We know he's starting to radicalize in 2009. ... I could speculate that he was probably going over there more often. We don't have -- I don't have the evidence of that just yet. But that's obviously an area of focus," he said. "I know the intelligence community is scrubbing through all their records and that travel is very important, just given who the Chechen rebels are."

Soon after returning from a long visit to Russia, Tsarnaev creates a YouTube channel with links to a number of videos. Two videos under a category labeled "Terrorists" have since been deleted. It's not clear when or by whom.

Analysis by CNN and the SITE Intelligence Institute has uncovered a screen grab from one of those videos. It features members of the group Imarat Kavkaz -- identifiable by the logo on their shirts. Imarat Kavkaz is the most potent militant Islamist group in the north Caucasus, which includes Chechnya and Dagestan.

Tsarnaev also appears to have posted and then removed a video of a militant named Abu Dujana, a jihadist leader who was later killed by Russian troops.

Russian security services killed Abu Dujana in December during an assault on an apartment in Makhachkala, the capital of Dagestan. He led a small militant group in Dagestan that had links to Imarat Kavkaz.

While Tsarnaev was in Russia in 2012, he spent some of his time in Makhachkala, where his father lives today. U.S. officials told CNN analyst Tom Fuentes on Sunday they have found no further connection between Tsarnaev and Abu Dujana, but the investigation into his activities overseas continues.

Tsarnaev presents an application for U.S. citizenship, according to The New York Times. The application prompted "additional investigation" of him in 2013 by federal law enforcement agencies, officials told the newspaper. The officials declined to say how far that examination had progressed or what it covered, the Times said.

When a preacher at the Islamic Society of Boston Cambridge mosque says that it is appropriate to celebrate U.S. national holidays such as July 4 and Thanksgiving, Tsarnaev stands up and challenges him, arguing that celebrating holidays is "not allowed in the faith," the Islamic Society of Boston said. After the sermon, Tsarnaev repeatedly argues his viewpoint with the preacher, then leaves.

When a preacher at the same mosque says slain civil rights leader Martin Luther King Jr. was a great person, Tsarnaev stands up, shouts and calls him a "non-believer," the Islamic Society of Boston said. Tsarnaev accuses the preacher of "contaminating people's mind" and calls him a hypocrite. People in the congregation shout back at Tsarnaev, telling him to "leave now." Leaders of the mosque later tell him he will no longer be welcome if he continues to interrupt sermons. At future prayers, he is quiet.

Two explosions go off near the finish line at the Boston Marathon, killing three people and injuring more than 170. Authorities describe the blasts as a terrorist attack and vow to bring whoever is responsible to justice.

5 p.m.: The FBI releases photos and videos showing two men they describe as suspects in the Boston Marathon bombings.

11 p.m.: Police respond to a call on the campus of the Massachusetts Institute of Technology, where university police officer Sean Collier, 26, has been shot. He dies from his injuries. Police later say they believe the bombing suspects were responsible for the shooting.

Tsarnaev dies after a shootout with police in Watertown, Massachusetts. Hours later, investigators reveal that he and his 19-year-old younger brother are the marathon bombing suspects.