In closing arguments before a jury decides whether Tsarnaev, 21, is guilty of the April 25 bombing and of fatally shooting a police officer three days later, Assistant US Attorney Aloke Chakravarty described the attack as deliberate and extremist.
"The defendant thought that his values were more important than the people around him. He wanted to awake the mujahedeen, the holy warriors," Chakravarty said. "He wanted to terrorize this country. He wanted to punish America for what it was doing to his people."
Tsarnaev, an ethnic Chechen who moved to the United States about a decade before the attack, could be sentenced to death if the jury that heard 16 days of testimony against him finds him guilty.
His lawyers opened the trial a month ago with a blunt admission, that "it was him" who carried out the attack. But they contended that Tsarnaev did so not out of his own ideological anger but out of a sense of subservience to his older brother, 26-year-old Tamerlan, who prosecutors say was his partner in the attack.
'EYE FOR AN EYE'
Chakravarty took that argument head on Monday, describing Tsarnaev's reading of al Qaeda's "Inspire" magazine.
"These were political choices," he said of Tsarnaev's actions. "He was making a statement, 'an eye for an eye.'"
Tamerlan died early on April 19, 2013, following a gunfight with police that ended when Dzhokhar sped off in a car, running his brother over in the process. Dzhokhar later found a hiding spot in a boat in a backyard, where he wrote a note suggesting the attack was an act of retribution for U.S. military campaigns in Muslim-dominated countries.
Tsarnaev's attorneys will deliver their closing argument later on Monday.
Monday's closing statements could be a preview of the arguments each side plans to make during the next phase of the trial, when the same jury will hear a fresh round of witness testimony before determining whether to sentence Tsarnaev to life in prison without possibility of parole, or to death.
The jury on Monday viewed video of Dzhokhar Tsarnaev standing with a backpack in the crowd at the marathon's finish line minutes before the blasts that killed restaurant manager Krystle Campbell, 29, Chinese exchange student Lingzi Lu, 23, and 8-year-old Martin Richard. Tsarnaev is also accused of the fatal shooting of Massachusetts of Institute of Technology police officer Sean Collier, 26.
Richard's parents, William and Denise; dancer Heather Abbott, who lost both legs in the blast, and former Boston Police Commissioner Ed Davis were among the people who packed the courtroom for closing arguments.
The defendant sat quietly in court on Monday, dressed in a white shirt, dark jacket and no tie. He did not speak.
But if he is found guilty, he may testify during the sentencing phase of his trial, legal experts said.
The surviellance video viewed by the jury on Monday shows a bomb, which the the defendant is charged with leaving in front of the Forum restaurant near the finish line, going off with a blinding flash, killing Richard and Lu. The jury also saw video taken by a man injured in the blast.
The graphic video captures the chaos of the immediate aftermath, with one responder yelling that he was worried about the possibility of an additional blast and another voice screaming, "We're on fire here. We're on fire."
