BOSTON (AP) First, the jury was shown large, vibrant pictures of the four people killed in the Boston Marathon bombing and its aftermath. Then prosecutors pulled out the photo they saved for last: Dzhokhar Tsarnaev giving the finger to the security camera in his jail cell.
''This is Dzhokhar Tsarnaev - unconcerned, unrepentant and unchanged,'' federal prosecutor Nadine Pellegrini told the jury that 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 Tuesday, 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.
''I remember hearing just bloodcurdling screams. I just remember looking around, just seeing blood everywhere, sort of like debris falling from the sky,'' said Celeste Corcoran, who made her way to the stand on two artificial limbs.
Several jurors shed tears as the father of Krystle Campbell, a 29-year-old restaurant manager killed in the bombing, described how he called his daughter ''princess.''
''Krystle was the light of my life,'' William Campbell Jr. said, ''every father's dream.''
He wiped away tears with a handkerchief, his voice growing hoarse as he described how she ''wasn't really a girly-girl'' and preferred baseball over other activities.
Campbell described a heartbreaking mix-up that led his family to believe that Krystle had survived the bombing and was undergoing surgery. One of the doctors asked Campbell to take a walk with him to go see Krystle in her room.
''It wasn't Krystle. I passed out on the floor,'' Campbell said. ''I couldn't remember anything after that until I woke up about five minutes later and I realized that Krystle was gone and they made a mistake.''
Earlier Tuesday, prosecutors showed the jury a photo of a wounded Krystle writhing in agony on the ground, her mouth agape.
Gillian Reny told the jury she was an 18-year-old high school senior when she went to watch her sister run her first marathon. She said the first blast knocked her to the ground, and when she looked down, she could see her legs were covered in blood, and a bone that had snapped in half was sticking out.
''Muscle was everywhere. It was the most horrifying image I could even imagine ... and to see that on my own body was terrifying,'' she said, breaking down in tears. Doctors managed to save both legs.
Slouching in his seat at the defense table as usual, Tsarnaev stared straight ahead and showed no reaction during the proceedings. He did not appear to look at any of the witnesses.
Three people were killed and more than 260 wounded in the bombing, carried out by Tsarnaev and his older brother, Tamerlan, to punish the U.S. for its wars in Muslim countries. An MIT police officer was shot to death days later as the brothers tried to get away.
Tsarnaev was convicted earlier this month of all 30 charges against him during the trial's guilt-or-innocence phase. His lawyers did not give an opening statement Tuesday but will do so once the prosecution has made its case.
The defense contends Tamerlan, 26, masterminded the bombing, and Dzhokhar, then 19, fell under his influence.
The 12-member jury must be unanimous for Tsarnaev to receive a death sentence; otherwise, he will automatically get life behind bars.
Prosecutors have argued that Tsarnaev was a full partner with his brother and deserves the ultimate punishment.
''His destiny was determined by him, and he was destined and determined to be America's worst nightmare,'' Pellegrini said. She described the killings as ''unbearable, indescribable, inexcusable and senseless.''
With enlarged photographs of the victims behind her in the courtroom, the prosecutor told the jury: ''They were all beautiful, and they're all now gone.''
''You know how they died. Now you need to know how they lived,'' she said. ''You need to know and to understand why their lives mattered.''
In a dramatic finish to her opening statement, Pellegrini placed between the victims' photographs the picture of Tsarnaev extending his middle finger. The security-camera image was taken three months after Tsarnaev's arrest.
''He had one more message to send,'' the prosecutor said.
The photo was not immediately released to the media because the prosecution has yet to authenticate it in court and enter it into evidence.
About a dozen people protesting against the death penalty demonstrated outside the federal courthouse Tuesday morning.
Earlier this week, the parents of the youngest of those killed, 8-year-old Martin Richard, urged prosecutors in a front-page letter in The Boston Globe to take the death penalty off the table.