Prosecutors on Thursday will urge a federal appeals court to uphold Boston Marathon bomber Dzhokhar Tsarnaev’s conviction and death penalty sentence.

Tsarnaev, and his older brother Tamerlan, carried out the 2013 attack which killed three people and wounded more than 260 others.

The U.S. Justice Department is expected to file a brief before the 1st U.S. Circuit Court of Appeals in Boston.