The fate of Boston Marathon bomber Dzhokhar Tsarnaev has been placed into the hands of jurors.

The 12-member panel will determine whether Tsarnaev should be put to death by lethal injection or spend the rest of his life in prison without the possibility of parole.

The 21-year-old was convicted last month on all 30 federal counts he faced in connection with the 15 April 2013 attacks that killed three people and injured 264 others.

He was also found guilty of the fatal shooting of an MIT police officer.

On Wednesday, attorneys from both sides made their final pitch to jurors in closing arguments.

Assistant US Attorney Steven Mellin urged the panel to vote in favour of the death penalty.

He called Tsarnaev a terrorist who showed no remorse and wanted to punish America.

Quoting a note Tsarnaev wrote prior to his capture, he said: "He wrote, 'Now I don't like killing innocent people, but in this case it is allowed because America needs to be punished.'

"These are the words of a terrorist who is convinced he did the right thing," Mr Mellin told the jury.

Tsarnaev’s defence asked the panel to keep an open mind as they considered his fate.

Attorney Judy Clarke said there was no excuse for what Tsarnaev did, but urged them to consider “who he is, who he was and who he might become”.

She asked jurors to try to understand how Tsarnaev, whom she described as a then-19-year-old “invisible kid” in the shadow of his radicalised older brother, became involved in the deadly bombings.

The defence called on several witnesses, including family members, in their bid to paint Tsarnaev as a kid who was pressured by his brother Tamerlan Tsarnaev.

The elder Tsarnaev, 26, was pronounced dead at the scene of a gun battle with police after his younger brother inadvertently ran him over with a car.