Tsarnaev arrives for jury selection in Boston Marathon bombing case

The trial is perhaps the most closely watched federal death penalty case since Timothy McVeigh was convicted and executed for the 1995 Oklahoma City bombing.

Boston Marathon bombing suspect Dzhokhar Tsarnaev has arrived for the start of jury selection in his federal death penalty trial. Those chosen for the jury will decide whether Tsarnaev planned and carried out the twin bombings that killed three people and injured more than 260 near the finish line of the race on April 15, 2013.

If they find him guilty, they will decide whether he should be put to death.

Potential jurors stared intently at Tsarnaev as he sat down at a table in the front of the jury assembly room. He was flanked by his attorneys.

Over the next three days, about 1,200 people will be called to federal court to be considered as potential jurors. The first 200 were given initial instructions Monday by Judge George O'Toole Jr.

People who lost loved ones or were injured in the 2013 bombings are searching for justice in one of the nation's most closely watched federal death penalty cases in two decades.

The courthouse is under tight security, with dozens of police officers inside and outside the building.

Jury selection is expected to take several weeks because of extensive media coverage. The process also could be slowed if potential jurors express objections to the death penalty.

Some legal observers say Tsarnaev's lawyers, facing powerful evidence against him, will probably focus their energies on the penalty phase, when they could present mitigating evidence to spare his life.

Prosecutors say 21-year-old Dzhokhar and his brother, Tamerlan Tsarnaev — ethnic Chechens who had lived in the United States for about a decade — carried out the bombings as retaliation for U.S. actions in Muslim countries. They are also accused of killing a Massachusetts Institute of Technology police officer. Tamerlan, 26, died after a firefight with police several days after the bombings.

Dzhokhar was captured later that day, wounded and bloodied, hiding inside a boat stored in a suburban yard. Prosecutors said he described a motive in a note written in the boat: "The U.S. Government is killing our innocent civilians" and "We Muslims are one body, you hurt one you hurt us all."

Tsarnaev's lawyers may lay the groundwork for some kind of mental health explanation, said Christopher Dearborn, a professor at Suffolk University Law School. That could include any persecution his family might have suffered as ethnic minorities in Kyrgyzstan, where the brothers spent most of their lives before moving to the U.S. with their parents and two sisters.

"I think the real value in that may be to start to try to generate even a little bit of empathy around this and humanize the kid a little bit, hopefully enough to save a life," Dearborn said.

The defense is expected to argue that Dzhokhar had a difficult childhood and was heavily influenced by his elder brother, who authorities believe became radicalized in the last few years of his life, including during a six-month trip to Dagestan and Chechnya in 2012.

Alice LoCicero, a Cambridge psychologist and terrorism expert who wrote a book, "Why 'Good Kids' Turn Into Deadly Terrorists: Deconstructing the Accused Boston Marathon Bombers and Others Like Them," said she believes Tsarnaev may have been susceptible to the influence of his brother and others because he had lost structure in the year before the bombings.

His parents moved to the volatile Dagestan region of Russia, and the family was having financial troubles. Authorities believe Tamerlan became radicalized in the last few years of his life, including during a six-month trip to Dagestan and Chechnya in 2012.

Prosecutors, however, say Dzhokhar showed signs before the bombings that he was becoming radicalized.

At least one of three college friends convicted of lying or impeding the investigation is expected to testify against him. An additional friend who pleaded guilty to possessing a gun used to kill a police officer during the manhunt is also expected to testify for the prosecution.

Supporters of Tsarnaev have demonstrated outside the courthouse during pretrial hearings.

Heather Abbott, who lost part of her left leg in the bombings, is one of several victims who plan to attend at least part of the trial. She said she hopes to gain some understanding of the motive.

"I don't see it as something that will get me past the horror of that day," she said. "It's something that I will always live with."