A carjack victim described his harrowing ride at gunpoint with the Boston Marathon Bombers and the moment he made “the most difficult decision” of his life to bolt from the car.

The victim, Dun Meng, testified Thursday during the federal death penalty trial of Dzhokhar Tsarnaev.

Prosecutors say Tsarnaev and his late brother, Tamerlan, planted two bombs that killed three people and injured more than 260 at the 2013 Boston marathon.

Three days later, Meng said Tamerlan Tsarnaev jumped into the front passenger seat of his car, pointed a gun at Meng's head and ordered him to drive.

"He pointed the gun to me. Right to my head," Meng testified in court. "He asked for money."

Meng detailed how the suspects forced him give them his ATM card and PIN number so they could withdraw money from his account. He later drove with the brothers to a gas station after they transferred items from a Honda Civic to Meng’s car, MyFoxBoston.com reported.

Meng, a young entrepreneur from China, testified that Tamerlan said, "he had just killed a police officer in Cambridge."

According to the Boston Globe, Meng indicated they were interested in driving to New York, but he said there wasn't enough gas for that. He also lied to them and said his 2013 Mercedes did not have a GPS system. 

Meng says he was able to escape and contact authorities when the Tsarnaevs stopped to get gas.

The jury was also shown autopsy photos of slain MIT Police Officer Sean Collier.

According to the Boston Herald, a woman serving on the jury wept while viewing the images and another juror covered her mouth and looked away as a picture of Collier’s face with a gunshot wound between his eyes appeared on the jury box monitors.

Collier was ambushed and shot six times the night of April 18, 2013, while patrolling, allegedly by Tsarnaev and his older brother Tamerlan, who was killed less than three hours later during a shootout with Watertown police.

Dr. Renee Robinson told the jury that Collier “essentially died right away” from severe brain trauma and inhaling his own blood.

The jury also saw crime scene photos from inside Collier’s blood-soaked cruiser, showing the casing from one of the bullets that killed him came to rest on his patrolman’s seat located on the front passenger seat, the Boston Herald reported.

The autopsy photos were shown to jurors but not to spectators in the courtroom.

The Associated Press contributed to this report