As the Boston Marathon bombing trial resumes in U.S. district Court in South Boston Monday, testimony will focus on the shootout and manhunt in Watertown, which left one police officer wounded.

The trial has taken us through various stages over six days of testimony and 51 witnesses: the explosions and resulting deaths and injuries, the weeklong search for the killers, identifying the Tsarnaevs, the murder of MIT police officer Sean Collier, and the carjacking of former Northeastern University student Dun Meng.

This week’s testimony begins where the carjacking victim left off on Thursday: with his leased Mercedes SUV reportedly commandeered by Dzhokhar and Tamerlan Tsarnaev and tracked to 87 Dexter Ave in Watertown, where a furious shootout between Watertown police and the the two brothers erupted.

Support for GBH is provided by:

Among the possible government witnesses this week is Andrew Kitzenberg, a former Watertown resident who spoke to WGBH News during our investigation of the shootout and manhunt, and who observed the violence from the third floor of 62 Laurel Street.

"I saw two men taking cover behind a dark SUV and they were shooting down Laurel Street towards officers and I couldn’t make out any true details because it was complete darkness out, but I could see two individuals kind of crouching and firing down the street, and I also had the vantage point of seeing at the end of the block the officers and there looked like there were about four or five vehicles at the end of Laurel Street," Kitzenberg said. "It really was a firefight."

Testimony this week about the shootout will also focus on the shooting of MBTA Police Officer Richard Donahue at the corner of Dexter Ave and Laurel Street in Watertown, which was believed to be the result of friendly fire. Laurel Street Resident Mike Doucette, whom we spoke with during our investigation of the manhunt, said police were aiming for Dzhokhar Tsarneav in the stolen SUV.

"They were shooting up the car as he tried to run over the two cops, when they jumped, and he ran over his brother," Doucette said. "And there was a cruiser right here — he rammed that cruiser with the front left bumper. That's when the brother came rolling out from underneath the car. And he hit that, and that's when they all started shooting at him, about right here, before he went through the intersection. That's when they shot the other cop in the leg."

"The cops shot the cop," he said.

Support for GBH is provided by:

Dzhokhar Tsarneav has been charged with 30 counts, and not one includes the wounding of Donahue, but he may play a role in the trial.

Throughout much of the testimony over the past two weeks the defense has crossed examined only a handful of the 51 witnesses. The defense has admitted that Dzhokhar Tsarnaev was involved in the bombing, the shooting of officer Sean Collier, the carjacking, and they do not dispute his role in the Watertown shootout. The question the defense is posing to the jury is why he did it. And they hope to demonstrate that he was far less culpable than his brother. The government is truing to prove that he was Tamerlan’s partner in crime, not a follower. If found guilty Dzhokhar Tsarnaev could be sentenced to death. Preventing that outcome is the main objective of Tsanaev’s defense team.