BOSTON (AP) — As jurors looked at a photograph of Boston Marathon bomber Dzhokhar Tsarnaev giving the finger to a security camera in his jail cell, a federal prosecutor described it as a defiant act by an unrepentant man who didn’t care that he had killed four people, including an 8-year-old boy and a police officer.

Assistant U.S. Attorney Nadine Pellegrini began laying out the government’s case for executing Tsarnaev, and showed the jury large, vibrant pictures of the people killed in the bombing and its aftermath. Then she revealed the photo of Tsarnaev, taken three months later in his holding cell at the federal courthouse.

“This is Dzhokhar Tsarnaev — unconcerned, unrepentant and unchanged,” Pellegrini on Tuesday told the jurors who will decide whether the 21-year-old former college student should be executed.

The penalty phase in the Boston Marathon bomber’s trial opened in dramatic fashion, with prosecutors portraying Tsarnaev as a coldblooded killer and “America’s worst nightmare.”

The government then began trying to drive home the horror of the attack by calling to the stand witnesses who lost legs or loved ones in the April 15, 2013, bombing.