The 21-year-old ethnic Chechen, who had not testified during his trial, referred to Allah and admitted that he and his now-dead older brother carried out one of the highest-profile attacks on U.S. soil, in a courtroom packed with survivors of the April 15, 2013 bombing.
"I am sorry for the lives I have taken, for the suffering that I have caused you, for the damage I have done, irreparable damage," said Tsarnaev, who had sat in silence, his head cast down as two survivors and family members of victims described the attacks' heavy toll on their lives.
"In case there is any doubt, I am guilty of this attack, along with my brother," Tsarnaev said, standing at the defense table.
Tsarnaev had been found guilty killing three people and injuring 264 in the bombing near the finish line of the world-renowned race, as well as fatally shooting a police officer three days later. The same federal jury that convicted him in April voted for death by lethal injection in May.
As he handed down that sentence, U.S. District Judge George O'Toole condemned Tsarnaev for falling under the spell of militant Islamists, including American-born al Qaeda figure Anwar al Awlaki, who was killed in a 2011 drone strike.
"It is tragic ... that you succumbed to their demonic siren song," O'Toole said. "As long as your name is mentioned, what will be remembered is the evil you've done."
After the sentencing, Tsarnaev asked forgiveness for himself and his dead brother.
"I ask Allah to have mercy upon me, my brother and my family," Tsarnaev said.
"I ask Allah to bestow his mercy upon those who are here today."
It could be years until Tsarnaev's legal process is finished. Death penalty sentences in the United States often take years to carry out, and there will be an appeal.
