The death penalty phase in the trial of convicted Boston Marathon bomber Dzhokhar Tsarnaev is set to begin on April 21.

Reuters noted that federal prosecutors and defense attorneys alike are preparing for the next phase of Tsarnaev’s trial in which one side will argue why he should die and the other why he should be spared.

The same jury that found the 21-year-old guilty of all 30 counts against him on Wednesday will decide his fate. The guilty verdict on those counts means that if he is not given the death penalty, he will spend the rest of his life in prison without the possibility of parole.

On April 15, 2013, two pressure cooker bombs exploded near the finish line of the Boston Marathon. The blast killed three people and injured more than 260 others. Tsarnaev and his older brother Tamerlan were seen on camera planting backpacks on the sidewalk before the bombs detonated.

In the days following the bombing, the pair got into a shootout with police in which one MIT officer was fatally shot. The eldest Tsarnaev brother was also shot and killed. The younger sibling sent police on manhunt in and around a city on edge before he was found and taken into custody.