Updated 9.46pm: The gruesome details of the Boston Marathon bombing victims have been recounted to jurors, as the US trial for a man accused of being behind the attack begins.

Prosecutors say Dzhokhar Tsarnaev carried out the attacks to avenge the deaths of Muslims overseas after learning how to build pressure-cooker bombs through Al-Qaeda propaganda.

He faces the death penalty if convicted of the bombings which killed three people and wounded more than 200 in 2013.

The defence will fight to take the death penalty off the table.

The 21-year-old American student, who's been accused of carrying out the bombings that killed three and injured 264 others, faces the death penalty if convicted.

Dzhokhar Tsarnaev has pleaded not guilty to 30 federal charges in connection with the attacks and the killing of a police officer.

The Guardian's US correspondent Nicky Woolf is in Boston where the trial is underway.

"It seems that defence is going to almost completely abdicate the first part of guilt and focus very much on making it look like Tsarnaev was in thrall to his brother, and avoid the death penalty in that way."

He says the defence has taken issue with the all-white jury, but the judge has refused to heed their concerns, including another motion to move the venue of the trial.

Nicky Woolf adds there's speculations it's virtually impossible to find a fair and impartial jury in Boston.