BOSTON — The prosecution in the Boston Marathon bombing trial started off the sentencing phase on Tuesday by showing an image of Dzhokhar Tsarnaev flipping off a security camera while in a court holding cell in July of 2013.

Though the prosecution called the action defiant, Tsarnaev’s defense attorneys released a portion of the cell surveillance video in an apparent effort to provide more context to the gesture.

In video, Tsarnaev finds the camera where it is mounted, steps up into close view, holds up a peace sign, then flashes a middle finger to the camera. After he flashed the offensive gesture, Tsarnaev goes back to the bench and sits down calmly.

Prosecutors seem to be building a case against Tsarnaev to show a lack of remorse for the havoc and sorrow he created. Jurors will determine whether Tsarnaev will receive the death penalty or life without parole.

Jurors also heard from family members of those who died in the blast on Tuesday.

In Boston courtroom, a procession of heartbreaking loss

Before Sean Collier was left to die in his patrol on a Thursday night in April 2013, he was Andrew Collier’s little brother.

As long as they can remember, Collier wanted to be a cop. He was a child who viewed life in terms of right and wrong. Either you did it or you didn’t.

“We thought it was typical little boy stuff, but he never grew out of it,” Andrew Collier told a federal jury Wednesday. The jury must decide whether Boston Marathon bomber Dzhokhar Tsarnaev, 21, should live or die for what he has done.

“Sean was always the one to spill the beans,” said Joe Rodgers, 59, who married Collier’s mother, Kelly, in 1993. “He was a cop from an early age.”

On a Thursday night in April 2013, Massachusetts Institute of Technology Police Officer Sean Collier lay bleeding in his patrol car after being ambushed and shot in the head. His car door was open, and his foot was lodged between the gas and brake pedals.

The officer who found Collier testified at trial that he had wounds to the temple, neck and head. He was bleeding out as officers tried to revive him. Collier would become the fourth victim of the Tsarnaev brothers.

The night still feels like a dream for Rodgers.

“He had a hole in the middle of his head,” Rodgers said. “He was shot to pieces. He was just laying there. My wife was touching him, and his blood was coming up in her hands.”

For a second day, the jury has witnessed a procession of heartbreaking loss including not only the family of Sean Collier, but also the survivors and the families of those killed when bombs planted by the Tsarnaev brothers exploded near the finish line of the 2013 Boston Marathon.

The twin bombings — carried out by Tsarnaev and his older brother Tamerlan — killed three people and hurt more than 240 others.

Prosecutors said the brothers killed Collier days later because they wanted his gun. But their efforts to take it were thwarted by a safety holster. Tamerlan, 26, was killed in a chase and gunbattle with police that began with reports of an “officer down” at MIT.

Less than two weeks after Tsarneav was found guilty on every count, the jury deciding his punishment is hearing about the lasting impact of his deeds.

The MIT police, who are designated as special officers by the Massachusetts State Police, patrol the sprawling campus in Cambridge.

MIT Police Chief John DiFava told the jury Wednesday that he hired Collier, who fit in “perfectly” because of his policing style and engaging personality.

“The atmosphere of the department changed since April 18, 2013,” he said. “There is sadness and a sense of loss. I think that it will be there for as long as that generation of officers remains. It was remarkable the amount of support we got from the community, but Sean’s death hangs like a weight.”

DiFava has come to question whether he wants to continue on the force.

“Policing is the only thing I’ve done in my life, and I’ve always tried to be good at what I do,” he said. “I lost one of my own. I have children at home and I’ve always thought I would have been very, very proud for them to wear the uniform. Now I’m not so sure.”

Rodgers said it took his wife Kelly months to gain the strength to climb out of bed after losing her son. Saturday was the second anniversary of the bombing. She cried the whole weekend.

“She was very strong,” he said. “She was a happy person. She was a good mother. Since Sean’s death, she’s very scared of anything that might happen to any of the other children.”

Kelly became pregnant with Sean after losing a baby that lived for a day or two, Rodgers said. His birth lifted her from depression.

“He was special,” he said, adding that Sean is now buried alongside the baby.

Rodgers said he still feels beat down two years later.

“There’s something missing,” he said. “Thanksgiving and Christmas will never be the same.”

Collier’s brother Andrew said, “Even when we’re having fun, there’s always a cloud over us. I miss Sean. I miss everything about him.”

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