Jurors in the United States are expected to begin deliberations on April 7 after closing arguments in the trial of accused Boston Marathon bomber Dzhokhar Tsarnaev.
Tsarnaev faces four counts of murder over the attack, in which bombs that exploded near the finish line of the April 2013 race killed three people and wounded 264.
The fourth murder charge is for the slaying of a police officer.
Tsarnaev, 21, could be sentenced to death if convicted.
His lawyers acknowledged that he placed two bombs in the crowd but argued that he did so under the influence of his radicalized older brother, Tamerlan, who was killed in a gunfight with police four days after the attack.
"We don't deny that Dzhokhar fully participated in the events, but if not for Tamerlan, it would not have happened," defense attorney Judith Clarke said.
But prosecutors say Dzhokhar Tsarnaev was an active participant and wanted to terrorize the United States.
If the 12-person jury in Boston convicts Tsarnaev, its members would then have to decide whether to sentence him to life in prison without the possibility of parole, or to death.
Tsarnaev, a U.S. citizen with roots in Russia's North Caucasus, lived in Kyrgyzstan for several years as a child.
Days after the bombings, he was found hiding 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 predominantly Muslim countries.
Prosecutors argued that he acted with deliberate malice.
"He wanted to terrorize this country. He wanted to punish America for what it was doing to his people," said Assistant U.S. Attorney Aloke Chakravarty. "He wanted to punish America for what it was doing to his people."
Chakravarty showed the jury a photo of the younger Tsarnaev standing close behind Martin Richard, an 8-year-old boy who was killed, and suggested he deliberately placed the bomb near Richard and other children.
"These children weren't innocent to him. They were American," the prosecutor said.
With reporting by AP, Reuters, and dpa