Attorneys for the convicted Boston Marathon bomber on Monday (11 May) rested their case that Dzhokhar Tsarnaev should be sentenced to life in prison without possibility of release rather than death for his role in 15 April 2013 attack.

The federal jury last month found Tsarnaev guilty of killing three people and wounding 264 others with a pair of homemade bombs at the famed race's crowded finish line. For the past three weeks, jurors have heard testimony from prosecution and defence witnesses.

Prosecutors, who are seeking the death penalty, contend the 21-year-old ethnic Chechen was an adherent of al-Qaeda's militant Islamic ideology who mounted the attack "to punish America" for US military campaigns in Muslim lands.

They showed the jury graphic video recorded moments after one explosion and a surveillance photo taken in a holding cell at Boston federal court while Tsarnaev awaited his first court appearance in July 2013, in which he extends his middle finger in a vulgar gesture.

Defence attorneys contend that he was a willing but secondary player in a scheme driven by his 26-year-old brother.

Tamerlan Tsarnaev died on 19 April 2013, following a gunfight with police that ended when Dzhokhar inadvertently ran him over while speeding away from the scene in a stolen vehicle.

Last week, defence attorneys called witnesses, including Russian relatives of Tsarnaev, who recalled him as a kind, loving child. One of Tsarnaev's aunts was so overcome at the sight of her nephew sitting at the defence table in federal court in Boston that she began crying and was unable to testify.

In seven days of testimony, Tsarnaev's public defenders have called 43 witnesses. After the defence rests its case, prosecutors will have the opportunity to call a few more rebuttal witnesses before each side gives its closing statement.

Tsarnaev, who had been a college student with poor grades at the time of the attack, has not spoken on his own behalf and is not obligated to take the witness stand.