Showing pictures of a defiant Dzhokhar Tsarnaev to convince the jury that he has no remorse, U.S. prosecutors are making their case to sentence him to death over the 2013 Boston Marathon Bombings.

Tsarnaev, a 21 year-old ethnic Chechen, has already been found guilty of carrying out the attack and fatally shooting a police officer as he tried to flee with his older brother, Tamerlan – killed shortly after in a shootout with police.

Prosecutors and defense attorneys are now arguing over whether Tsarnaev should die or spend the rest of his life in jail.

Opponents of the death penalty rallied outside the courthouse on Tuesday as the sentencing phase of the trial began. It is expected to last several weeks.

Three people were killed and 264 injured when two pressure-cooker bombs left by the Tsarnaev brothers exploded near the Boston Marathon’s finish line.