Victims of the the Boston Marathon blasts have condemned the bomber after he apologised for the attack.
Dzhokhar Tsarnaev broke his silence on the death and devastation he caused two years ago with words that were not a political tirade or a justification.
He apologised to victims and their families at his formal sentencing in federal court in Boston.
"I am sorry for the lives that I've taken, for the suffering that I've caused you, for the damage that I've done - irreparable damage," the 21-year-old former college student said, speaking haltingly with a heavy accent.
A runner sits near Kenmore Square after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 23 injured after two explosions went off near the finish line to the marathon.
A woman is helped from the scene near the finish line after two bombs exploded during the 117th Boston Marathon on April 15, 2013 in Boston, Massachusetts. Two people are confirmed dead and at least 28 injured after at least two explosions went off near the finish line to the marathon.
Boston Police stand near the scene of a twin bombing at the Boston Marathon, on April 16, 2013 in Boston, Massachusetts. Three people are confirmed dead and at least 141 injured after the explosions went off near the finish line of the marathon.
Honor guards stand beside a wreath at the site of one of the two bomb blasts on the one-year anniversary of the 2013 Boston Marathon bombings in Boston, Massachusetts, April 15, 2014. REUTERS/Dominick Reuter (UNITED STATES - Tags: SPORT ATHLETICS DISASTER ANNIVERSARY)
A Boston Marathon bombing survivor receives a hug next to the site of the first bomb explosion on Boylston Street in Boston, Massachusetts in this April 24, 2013 file photo. Tuesday marks the one-year anniversary of the Boston Marathon bombing on April 15, 2013, when two Chechen brothers allegedly planted pressure-cooker bombs near the race's finish line, killing three people and wounded more than 260. REUTERS/Brian Snyder
Flowers lie on the sidewalk at the site of the first explosion as people walk along Boylston Street after the street reopened to the public for the first time since the Boston Marathon bombings in Boston, Massachusetts in this April 24, 2013 file photo. Tuesday marks the one-year anniversary of the Boston Marathon bombing on April 15, 2013, when two Chechen brothers allegedly planted pressure-cooker bombs near the race's finish line, killing three people and wounded more than 260. REUTERS/Jessica Rinaldi
A peace sign is seen on a message tree as visitors look at artefacts in a public exhibition of objects and mementos left at the makeshift memorials that emerged in the aftermath of the Boston Marathon Bombings in Boston, Massachusetts, April 7, 2014. REUTERS/Dominick Reuter
Prosecutor Carmen Ortiz said Tsarnaev's statement was more noteworthy for what he did not say.
"He didn't renounce terrorism. He didn't renounce violent extremism," she said.
After Tsarnaev said his piece, US District Judge George O'Toole Jr quoted a line from Shakespeare: "The evil that men do lives after them. The good is often interred with their bones."
"So it will be for Dzhokhar Tsarnaev," the judge added, telling the bomber that no one will remember that his teachers were fond of him, that his friends found him fun to be with or that he showed compassion to disabled people.
"What will be remembered is that you murdered and maimed innocent people, and that you did it wilfully and intentionally," Judge O'Toole said.
Tsarnaev looked down and rubbed his hands together as the judge announced he would be executed, the punishment decided by a jury last month for the 2013 attack that killed three people and wounded more than 260.
The apology came after Tsarnaev listened for about three hours as a procession of 24 victims and survivors lashed out at him for his "cowardly" and "disgusting" acts.
"He can't possibly have had a soul to do such a horrible thing," said Karen Rand McWatters, who lost a leg in the attack and whose best friend, 29-year-old Krystle Campbell, was killed.
Ms Campbell's mother Patricia looked across the room at Tsarnaev, seated about 20ft away, and spoke directly to him.
"What you did to my daughter is disgusting," she said. "I don't know what to say to you. I think the jury did the right thing."
Rebekah Gregory, a Texas woman who lost a leg in the bombing, defiantly told Tsarnaev she was not his victim.
"While your intention was to destroy America, what you have really accomplished is actually quite the opposite - you've unified us," she said, staring directly at Tsarnaev.
Bill Richard, whose eight-year-old son Martin was the youngest person killed in the bombing, noted that his family would have preferred that Tsarnaev receive a life sentence so he could contemplate his crimes.
Mr Richard said his family had chosen love, kindness and peace, adding: "That is what makes us different than him."
Tsarnaev assured the survivors he was paying attention to their words.
"All those who got up on that witness stand and that podium relayed to us, to me - I was listening - the suffering that was and the hardship that still is, with strength and with patience and with dignity," he said.
The judge was required under the federal death penalty law to impose the jury's death sentence for an attack prosecutors said was carried out by Tsarnaev and his older brother Tamerlan, to retaliate for US actions in Muslim countries.
Tamerlan, 26, was killed during a getaway attempt days after the bombings.
Tsarnaev's apology was peppered with religious references and praise of Allah. He asked that Allah have mercy upon him and his dead brother.
Tsarnaev will almost certainly be sent to the death row unit at the federal penitentiary in Terre Haute, Indiana, where Oklahoma City bomber Timothy McVeigh was executed. It could take years or even decades for his appeals to work their way through the courts.