A US appeals court has overturned the death sentence given to Dzhokhar Tsarnaev for the deadly bombing attack at the 2013 Boston Marathon.
Three people were killed and more than 260 injured when two bombs planted by Tsarnaev and his brother exploded at the finish line.
The court said Tsarnaev would spend the rest of his days in prison.
However, it ordered a retrial over the sentence for the crimes, which can carry the death penalty.
In its ruling, the court said the trial judge had failed to exclude jurors who had already concluded that Tsarnaev was guilty.
Tsarnaev and his elder brother Tamerlan, both Kyrgyz-American nationals of Chechen descent, planted bombs close to the finish line of the Boston Marathon on 15 April 2013.
Tamerlan was killed in a shootout with police three days later.
Dzhokhar Tsarnaev fled the shootout and was captured a day later, after being found hiding in a boat in the backyard of a house in Watertown - a suburb of Boston.