BOSTON (AP) — A jury sentenced Dzhokhar Tsarnaev to death Friday for the Boston Marathon bombing, sweeping aside pleas that he was just a “kid” who fell under the influence of his fanatical older brother.

Tsarnaev, 21, stood with his hands folded upon learning his fate, decided after 14 hours of deliberations over three days in the nation’s most closely watched terrorism trial since the Oklahoma City bombing case two decades ago.

The decision sets the stage for what could be the nation’s first execution of a terrorist in the post-9/11 era, though the case is likely to go through years of appeals. The execution would be carried out by lethal injection.

The 12-member jury had to be unanimous for Tsarnaev to get the death penalty. Otherwise, he would have automatically received a sentence of life in prison without parole.

Three people were killed and more than 260 wounded when two pressure-cooker bombs packed with shrapnel exploded near the finish line on April 15, 2013.

Tsarnaev was convicted last month of all 30 federal charges against him, including use of a weapon of mass destruction and the killing of an MIT police officer during the Tsarnaev brothers’ getaway attempt. Seventeen of those charges carried the possibility of the death penalty.

Tsarnaev’s chief lawyer, death penalty specialist Judy Clarke, admitted at the very start of the trial that he participated in the bombings, bluntly telling the jury: “It was him.”

But the defence argued that Dzhokhar was an impressionable 19-year-old who was led astray by his volatile and domineering 26-year-old brother, Tamerlan, who wanted to punish the US for its wars in Muslim countries.

Prosecutors portrayed Dzhokhar Tsarnaev as an equal partner in the attack, saying he was so heartless he planted a bomb on the pavement behind a group of children, killing an 8-year-old boy.

To drive home their point, prosecutors cited the message he scrawled in the dry-docked boat where he was captured: “Stop killing our innocent people and we will stop.” And they opened their case in the penalty phase with a startling photo of him giving the finger to a security camera in his jail cell months after his arrest.