BOSTON — Lawyers for convicted Boston Marathon bomber Dzhokhar Tsarnaev on Tuesday are set to probe his troubled family history as they make their plea for a jury to sentence him to life in prison rather than death. The 21-year-old ethnic Chechen was convicted earlier this month of killing three people and injuring 264 in the April 15, 2013, bombing, as well as shooting dead a police officer three days later alongside his older brother, Tamerlan Tsarnaev. Defense attorneys opened their case on Monday by arguing that 26-year-old Tamerlan, who died following a gunfight with police hours after the police officer's shooting, was the driving force behind the attack and that his younger brother had been raised to follow his lead. During the first day of defense witness testimony, the jury heard from people who had seen Tamerlan's outbursts at a mosque near his Cambridge, Massachusetts, home and from his mother-in-law, who described his growing obsession with religion. Martin Richard, 8, Chinese exchange student Lu Lingzi, 23, and restaurant manager Krystle Campbell, 29, died in the bombing. Massachusetts Institute of Technology police officer Sean Collier was shot dead three days later. Richard's parents and Collier's sister have urged prosecutors to drop their pursuit of a capital sentence, saying a deal in which Tsarnaev would accept a life sentence in exchange for giving up his appeal rights would allow the incident to fade from the spotlight more quickly. One of Tsarnaev's attorneys echoed that sentiment in his opening statement on Monday. Federal prosecutors previously cited Al-Qaeda materials found on Tsarnaev's computers and a note suggesting that the attack was an act of retribution for US military campaigns in Muslim-dominated countries. They also showed the jury a surveillance photo taken in a holding cell at Boston federal court while Tsarnaev awaited his first court appearance in July 2013, in which he extends his middle finger in a vulgar gesture. Defense attorney David Bruck noted that image came at the end of a 30-second video in which Tsarnaev also fussed with his hair in the mirror covering the security camera. Bruck urged the jurors to consider a new side of Tsarnaev over the next two weeks. “You can't ever accurately evaluate anything, not even a picture, until you know the context,” Bruck said. “Whether it's a grainy still from a surveillance camera or a young man's life, you have to know the context.” — Reuters