The best chance to save the life of Boston Marathon bombing suspect Dzhokhar Tsarnaev might be to put his dead brother on trial.

When Tsarnaev’s case begins, his lawyers are likely to pin their hopes — and the bombings themselves — on his older brother, Tamerlan: a Golden Gloves boxer, college student, husband and father who also followed radical Islam was named by a friend as a participant in a grisly 2011 triple slaying.

“He was the eldest one and he, in many ways, was the role model for his sisters and his brother,” said Elmirza Khozhugov, the former husband of Tamerlan’s sister, Ailina.

“You could always hear his younger brother and sisters say, ‘Tamerlan said this,’ and ‘Tamerlan said that.’ Dzhokhar loved him. He would do whatever Tamerlan would say,” Khozhugov told The Associated Press in the weeks after the bombings.

Three people were killed and more than 260 were injured when two homemade pressure-cooker bombs exploded near the finish line of the iconic race on April 15, 2013.

Tamerlan Tsarnaev, 26, died days after the bombings following a gun battle with police. Dzhokhar, then 19, was later found hiding in a boat parked in a backyard. Jury selection in his federal death penalty trial is entering its second month.

Dzhokhar’s lawyers have made it clear they will try to show that he was heavily influenced, maybe even intimidated, by his older brother, into participating in the bombings.

If a jury convicts Dzhokhar, its decision on whether to give him life in prison or sentence him to death could depend “on the extent to which it views Tamerlan Tsarnaev as having induced or coerced his young brother” to help commit the crimes, the defense argued in a court filing.

About a decade before the attack, their parents, ethnic Chechens, had moved the family to the U.S. from the volatile Dagestan region of Russia after living in the former Soviet republic of Kyrgyzstan. Their father, Anzor Tsarnaev, told The Associated Press the emigrated in part to escape discrimination.

The relationship between the two brothers would likely be a key part of the evidence Dzhokhar’s lawyers present even if he’s convicted, said David Hoose, who represented a Massachusetts nurse who was spared the federal death penalty in the killings of four patients.

Under the federal death penalty law, juries deciding on a sentence can consider whether a defendant “was under unusual and substantial duress,” regardless of whether duress is used as a defense to the charges. If the defense is allowed to use evidence of Tamerlan’s possible involvement in the triple murder, they could argue that Dzhokhar was under duress to participate in the marathon bombings, Hoose said.

Prosecutors have said that a friend of Tamerlan, Ibragim Todashev, implicated him in the killings of three men in Waltham whose bodies were found sprinkled with marijuana, their throats cut. Todashev was shot to death by an FBI agent after authorities said he charged another investigator with a pole while being questioned about the Tsarnaevs.

“If they can show that the older brother is gruesomely involved in the murders, all the more reason that Dzhokhar felt that not only is he my brother — he is someone not to fool around with. I have to do what he says,'” Hoose said.

Tamerlan’s high school friends say he appeared to adjust well to his life in America.

“As a student, he was like the rest of us,” said Luis Vasquez, who became friends with Tamerlan soon after he moved to Cambridge. “You could catch him in the library doing work, socializing in the hallways with people he knew, or at a local pizza shop we could go to during lunch.”

About the same time, Tamerlan took up boxing. He was a success, becoming the Golden Gloves heavyweight champion of New England in 2009 and 2010.

“He was a determined guy, in good shape, a strong guy,” said Bob Russo, then-coach for the New England team. “There was nothing unusual about him.”

After he was barred from competing in a national tournament because he was not a U.S. citizen, Tamerlan drifted away from boxing.

He took classes at Boston’s Bunker Hill Community College for a short time, but dropped out. In 2010, he married Katherine Russell, a Rhode Island woman he met at a nightclub, and the couple had a daughter together.

Authorities believe Tamerlan’s beliefs became radical during the last few years of his life.

In March 2011, Russian officials told the FBI that Tamerlan was a follower of radical Islam. The FBI interviewed Tamerlan, but closed its investigation several months later after finding nothing linking him to terrorism.

In 2012, Tamerlan spent six months in the southwest Russian regions of Chechnya and Dagestan, where authorities have said they suspect he tried to join insurgents, but was unsuccessful.

After returning to the U.S., Tamerlan was twice asked to leave a mosque over outbursts. The first time, he stood up at the Islamic Society of Boston Cultural Center and argued with a preacher who said it was appropriate for Muslims to celebrate U.S. holidays. Two months later, he called a preacher who praised civil rights leader Martin Luther King Jr. a “non-believer” who was “contaminating people’s minds.” Mosque leaders said they told him he would not be welcome if he interrupted again and he did not cause any more problems.

In their court filings, Dzhokhar’s lawyers have asked prosecutors for any evidence “showing that Tamerlan’s pursuit of jihad predated Dzhokhar’s” because that “would tend to support the theory that Tamerlan was the main instigator of the tragic events that followed.”

But prosecutors are prepared to argue that Dzhokhar was a full and willing participant in the bombings. They cite a message scrawled inside the boat he was found hiding in, indicating that the bombings were meant to retaliate against the U.S. for the deaths of civilians during the wars in Iraq and Afghanistan.

“I can’t stand to see such evil go unpunished,” he wrote, according to excerpts filed in court.

“Stop killing our innocent people and we will stop.”

(AP)