Boston Marathon bombing: Jurors shown dramatic carjack video as Tsarnaev prepares defence

A courtroom sketch shows accused Boston Marathon bomber Dzhokhar Tsarnaev in court on the second day of his trial (Reuters)

Prosecutors in the trial of accused Boston Marathon bomber Dzhokhar Tsarnaev have brought 51 witnesses before jurors in the first six days, with the hearing resuming today as the case moves towards the final hours before the ethnic Chechen was caught by police.

Last week, dramatic footage showed not only Tsarnaev and his late brother, Tamerlan, in the moments before the fatal bombing that killed three and injured 264, but also their movement afterwards.

With Dzhokhar's lawyers not arguing his innocence but rather that his older brother masterminded the attacks, a string of witness statements and video surveillance has been utilised by the prosecution to counter that Dzhokhar was just as guilty as his late brother Tamerlan.

One video centred around the carjacking of Dun Meng, which police allege occurred shortly after the bombers shot and killed a policeman on the Thursday after the bombings.

Meng said he had gone for a relaxing drive after work on April 18, 2013 when Tamerlan Tsarnaev stepped into his car and pulled out a gun.

"He pulled the magazine out of the gun to show me there's bullets in the gun. He told me, 'You know, I'm serious, so don't be stupid,'" Meng told the court.

Meng claimed that Tamerlan told him that he had caused the Boston Marathon explosion and that he had just killed a policeman.

CCTV video shows Meng escaping from his hijacked Mercedes when Dzhokhar had gone to get food at a petrol station while Tamerlan was busy figuring out the navigation system in the vehicle.

"This seems the most terrifying moment, most difficult decision in my life," Meng said. Meng alleged that Tamerlan had told him he would not be killed, but he did not know whether he could trust that statement.

"I was struggling, should I trust him about that? Or should I take this chance by myself to run away?"

Video shows Meng running out of the car and across the road to a Mobil gas station, where he is seen talking to the cashier at the counter. He then makes his way to the back of the store and dials 911, with audio of the call revealed to the court.

This call helped police locate the brothers and led to Tamerlan's death and Dzhokhar's capture. When Tamerlan realised Meng had run off, the pair drove off before engaging in a gunfight with police. The shooting ended when Dzhokhar drove off in Meng's Mercedes, running over and killing his brother before disappearing and hiding in a boat.

It is still not known whether 21-year-old Dzhokhar will be asked to testify by his defence team.

Additional reporting by Reuters.