The same jury found Tsarnaev guilty last month of placing a pair of homemade pressure-cooker bombs on April 15, 2013, as well as fatally shooting a policeman. The bombing was one of the highest-profile attacks on U.S. soil since Sept. 11, 2001.

Tsarnaev, dressed in a dark sport coat and light-coloured shirt, stood quietly as the sentence was read, remaining expressionless as he had throughout most of the trial. During 10 weeks of testimony, jurors heard from about 150  witnesses, including people whose legs were torn off by the shrapnel-filled bombs.

Prosecutors described Tsarnaev, who is an ethnic Chechen, as an adherent of al Qaeda's militant Islamist views who carried out the attack as an act of retribution for U.S. military campaigns in Muslim-majority countries.

Latest News from World News Desk