Federal prosecutors say the devastating bomb blasts that struck the 2013 Boston Marathon were the result of a deliberately cruel plan by Dzhokhar Tsarnaev and his older brother, Tamerlan.
Defense lawyers counter that the younger Tsarnaev was raised in a dysfunctional family and was "submissive" to his brother, who hatched the plot.
On Wednesday a federal court jury in Boston will begin hearing the case as lawyers for both sides make their opening statements.
The 12 jurors and six alternates were chosen during a selection process that took two months and brought claims from Tsarnaev's lawyers that he could not get a fair trial in a city where nearly everyone was touched by the bombing or the aftermath.
A single question will dominate the trial, expected to last several months: What penalty will the jury impose?
"My guess is, most of this case is going to center on whether he gets the death penalty or not," says Prof. Robert Bloom of Boston College Law School.
David Bruck, a member of the defense team, made the same point in a court hearing on Monday. "This case is all about sentencing," he said.
"I feel like I need to be there, and I know it's going to be difficult. And I know there are going to be a lot of things that are going to be painful."
While many victims of the bombing say they just want the trial over and done with, some say they will attend at least part of it.
Karen Brassard has no feeling on her lower right side, an injury from bomb shrapnel that struck her left ankle and right leg. She wants to see Tsarnaev in court for herself.
"I feel like I need to be there, and I know it's going to be difficult. And I know there are going to be a lot of things that are going to be painful."
Tsarnaev faces charges that could bring the death penalty in the bombings that killed three people and injured 260 others nearly two years ago and in the shooting death of an MIT police officer, Sean Collier, three days later.
Prosecutors say the brothers assembled bombs inside pressure cookers, put them in backpacks, and placed them about a block apart, in the midst of the crowd watching the marathon runners near the finish line.
Four days later, Tamerlan was dead in a police shootout, and Dzhokhar was found hiding in a boat stored in a backyard, wounded by police gunfire.
The government says he scrawled criticism of the American military on the inside of the boat, including "The US is killing our innocent civilians" and "I can't stand to see such evil go unpunished."
Tsarnaev was 19 at the time of the bombings. His lawyers claim he was dominated by his older brother — someone he feared and respected.
Defense attorney David Bruck on Monday called Tamerlan Tsarnaev "the lead conspirator, but for whom the marathon bombing would never have happened."
Legal experts say that because the government's evidence appears to be so strong, the best hope for the defense is to cast Tsarnaev as under the thumb of his brother.
"The defense will have to do whatever they can to generate sympathy for this young man. And the best chance they have to generate sympathy for him is this relationship with his brother," said Pete White, a Washington, DC lawyer and former federal prosecutor.
Defense lawyers have also said Tsarnaev was raised by a father who was distant and a mother who was becoming a religious fanatic.
The trial will be conducted in two phases. First jurors must decide if he is guilty. If they convict him on the counts punishable by death, they will then decide whether he should be sentenced to death or life in prison without parole.
NBC News' Andy Thibault contributed to this report.
