Judging by the way Dzhokhar Tsarnaev acted in surveillance footage shown in court on Thursday afternoon, you may never have guessed that he, or his brother, pulled the trigger that sent three bullets into the brain of MIT Police Officer Sean Collier.

On April 18, the night Collier was fatally shot while sitting in his cruiser on the campus of MIT, an SUV not registered to either Dzhokhar or his brother Tamerlan pulled up to a pump at Allan Mednick’s Shell gas station on Memorial Drive in Cambridge.

A man emerged from the vehicle wearing the same sweatshirt MIT student Nathan Harman testified Dzhokhar was wearing when Harman rode his bicycle past Collier’s cruiser at roughly 10:24 p.m. on that night.

A composite surveillance video from the gas station showed Tsarnaev enter the convenience store and proceed to gather concessions. The footage then cuts to an exterior shot of a second man emerge from the car and run out of frame, followed by a third person assumed to be Dzhokhar’s older brother Tamerlan.

Tamerlan then enters the convenience store, has words with Dzhokhar, and the two rush outside and back into the vehicle before pulling away.

The second man to exit the vehicle was Dun Meng, who was leasing the Mercedes sport utility he testified in court on Thursday the Tsarnaev brothers jacked at gunpoint.

Meng delivered some of the more gripping (ands less gruesome) testimony of the trial thus far, providing a more introspective look at how the Tsarnaevs thought and acted than previously known.

Meng was taken for the ride of his life the night of April 18 and not at all in a good way. After calling it quits from work at around 10:30 p.m., Meng decided to take a relaxing drive along the Charles Rivers on Memorial Drive.

After making his way across the Charles, Meng found himself on Brighton Avenue, having just pulled over to respond to a text message when he saw another vehicle quickly pull up behind him.

A man proceeded to Meng’s SUV, tapped on the window and once Meng rolled it down (thinking the person was asking for directions), he was in the passenger’s seat with a gun pointed in Meng’s face.

The man, Meng testified, was Tamerlan Tsarnaev.

Tamerlan, Meng testified further, told him he was the Boston Marathon bomber and that he, that same evening, fatally shot MIT Police Officer Sean Collier.

In court this proved an interesting wrinkle because on Wednesday, MIT student Nathan Harman testified that he saw Dzhokhar leaning into Collier’s cruiser the night the officer was shot in the head. In opening statements, Dzhokar’s defense team alluded t0 Tamerlan as the one who “shot and killed Officer Collier.”

Tamerlan proceed to steal the cash Meng was carrying on him as well as his ATM bank card.

Eventually Meng took Tamerlan to Dexter Street in Watertown where they pulled over and a sedan pulled up behind.

Tamerlan ordered Meng into the front passenger’s seat, and proceeded to load unknown items into the back of the SUV. Then Dzokhar climbed into the back.

With Tamerlan now driving, the three proceeded to an ATM where Dzhokhar withdrew $800 and tried to withdraw an additional $800 twice but was denied, as verified by William O’Keefe, Bank of America vice president of corporate security for the protective service division assigned to Boston.

Running low on gas, they arrived at a station that was closed, returned to the sedan on Dexter seat to retrieve a CD that Meng described was in a foreign language and “religious” and then something unexpected happened: Meng’s roommates tried to get in touch.

The first roommate tried calling and eventually sent a text warning Meng to be careful.

The second roommate called at which point Tamerlan became visibly nervous.

“[Tamerlan] put the gun to my head and said ‘if you say anything in Chinese, I’ll kill you right now.'”

Like Meng, his roommates were Chinese and conversed predominantly in Mandarin. Meng hurridly told the roommate he was staying at a friends house and hung up.

Subsequently the car pulled into a cash-only Shell gas station on Memorial Drive. Dzhokhar, as seen by Mednick’s surveillance footage, went inside to pay for gas and concessions. Tamerlan was in the front seat of the car, his gun stashed in the pocket in driver’s side door, with both hands on a GPS system thought to have been retrieved along with the religious CD.

That’s when Meng unbuckled his seat belt, opened the door and, escaping Tamerlan’s attempted grab, bolted across the street to Memorial Mobil where he literally begged the attendant to dial 9-1-1.

Shell surveillance footage shows Tamerlan exit the car, open the door to the convenience store and get Dzhokhar’s attention, and then the two rush to return to the car and drive away.

The defense took the opportunity to cross-examine Meng, who said he never once saw a gun in the hand of Dzhokhar. The defense’s stance is that Tamerland led every move in the bombing and aftermath and that Dzhokhar was influenced to follow along.

The prosecution was quick to note conversely, however, that Dzhokhar never said he wasn’t carrying a firearm.

Police would ultimately trace Meng’s car to Watertown where they would engage the two brothers in a firefight. Explosives would be lobbed at the authorities, lending credence to the notion that this was what was loaded into the back of Meng’s car, and Tamerlan would be run over by his brother and killed.

Dzhokhar would find his way to a dry docked boat nearby where he was captured.