BOSTON -- Inside a gas station mini-market, a lanky young man grabs canned drinks from a fridge and a few bags of snack food. Curly hair pokes out from under the shopper's hooded sweatshirt as he strolls the aisles stroking his chin.
This calm customer is 19-year-old Dzhokhar Tsarnaev, shown in video footage from shortly after he and his brother Tamerlan allegedly killed MIT Police Officer Sean Collier on April 18, 2013, in Cambridge, Massachusetts.
Though it would be nearly another day before police netted Dzhokhar, this video marks the beginning of the end of the Tsarnaev brothers' violent spree that gripped greater Boston along with the rest of the country.
Compiled from security cameras, the images are part of two recordings that were presented to jurors in federal court on Thursday, as part of the prosecution's case against Dzokhar Tsarnaev. He has pleaded not guilty to 30 charges stemming from the double bombing of the Boston Marathon that killed three people and wounded 264.
The video shifts outside the store and shows a man dashing past fuel pumps and across the street to another gas station. That figure is Dun Meng, the Chinese engineer whom the Tsarnaevs had allegedly carjacked and held hostage inside his Mercedes SUV.
Meng's sprint to freedom throws Tamerlan and Dzhokhar into a sudden panic. Tamerlan races to the mini-market's entrance and gets his brother's attention. Dzhokhar rushes to leave, but as he's about to exit, he stops. He turns back and puts down the merchandise.
It's ironic that the man who admits to bombing the Boston Marathon would be reluctant to shoplift an armful of snacks.
The end of the recording shows the SUV driving away from the gas station.
The second video focuses on Meng's escape and includes a recording of his frantic 911 call.
In court proceedings Thursday afternoon, Meng explained how he came to be in the car at the gas station. He testified that earlier that day, he'd been sitting in his car near the Charles River and sending text messages when Tamerlan, armed with a handgun, forced his way into his vehicle. “Do you know the Boston Marathon explosion?" Tamerlan asked, according to Meng's testimony. "I did it and I just killed a policeman."
Tamerlan took all the cash Meng had -- about $40 -- and forced him to drive around Cambridge. Dzhokhar followed behind in a sedan, Meng told jurors.
After making some stops, Dzhokhar abandoned the sedan and joined the other two in the Mercedes. Tamerlan took the wheel and Meng slid over to the passenger seat.
Meng said he was "terrified" as Tamerlan twice pointed a gun at him and threatened to kill him.
Eventually they pulled into the Shell gas station where the first video was recorded. With Dzhokhar perusing the convenience store and Tamerlan fidgeting with a GPS device in the driver's seat, Meng recognized that the time was right for him to escape.
The second video begins with Meng running to the nearby Mobil gas station, and then switches to footage from a camera inside that station's convenience store. Meng appears very animated in his discussion with the clerk behind the counter. He points outside with one arm while holding the door shut with the other, as if to prevent anyone from following him inside. Then, Meng crouches down and crawls to the back of the store while the clerk calls 911.
"Please help me. Please help me," Meng says to the operator when handed the phone. 'Someone took my car … They have guns.
"They are the suspects in the marathon explosions," Meng seems to say.
Meng's emergency call helped police find Tamerlan and Dzhokhar Tsarnaev, according to testimony from members of the Cambridge Police Department who took the stand later in the afternoon.
After speaking with Meng, the cops contacted Mercedes' security department, which used a tracking device to locate Meng's stolen SUV in nearby Watertown.
The Tsarnaevs, heavily armed with a gun, knives and additional homemade explosives, were inside the vehicle. Police hurried there and engaged in gunfight with the brothers. Tamerlan died after he was shot several times and eventually run over by Dzokhar, who was attempting to escape in the car. Dzhokhar ran away and hid in a motorboat covered in a tarp, eluding police there for hours before eventually getting arrested.