One of the men charged in the first-degree murder of a McMaster University student says police have a video of the killing — and he's not the one pulling the trigger.

Josh Barreira, one of six accused in the shooting death of Tyler Johnson, says security cameras captured the moment of the murder and show one of his co-accused firing the fatal shot.

He says the co-accused pulls a gun from the waistband of his pants, "pivots and walks right past me toward Tyler."

According to Barreira, the video then shows his co-accused being punched in the face by Tyler.

"He stumbles down, gets back up and shoots him ... He shoots him once."

Tyler, who had just earned a scholarship for a master's degree in mechanical engineering at Mac, was gunned down Nov. 30, 2013, outside Vida La Pita on King Street West. Tyler was 30.

Barreira, 26, his brother Brandon Barreira, 19, Chad Davidson, 34 and Louis Rebelo, 26 are charged with first-degree murder. Jennifer Dagenais, 28, (Josh's partner), and Ashley Dore-Davidson, 27, (Chad's partner), are charged with being an accessory after the fact to murder.

Police described Tyler's murder as a "co-ordinated attack carried out by a number of suspects."

Barreira requested I visit him at the Hamilton-Wentworth Detention Centre so he could tell me about the video. He says it proves he is innocent of murdering Tyler.

"Just being with somebody when they kill somebody is not a crime," he says. "Why am I in jail?"

I spent an hour with Barreira. He has a shaved head, a bit of facial hair, tattoos on his arms, black rimmed glasses. He spoke softly and slowly.

His claim of innocence is interesting on many levels.

First, it has never been made public that the moment of the murder was captured on video.

Tyler's mom Linda Johnson confirms it is true. She says she has been told what is on the video but has not been able to bring herself to watch her son's final moments.

"For obvious reasons," she says.

Neither Barreira's lawyer, Daniel Moore of Toronto, assistant Crown attorney Cheryl Gzik, nor Hamilton police Staff Sergeant Paul Hamilton would confirm the murder is on video.

Hamilton, the major case manager, did say however that the brief video images police released at the time of the murder in the hopes of identifying suspects was only "a snippet" of the video they have.

Barreira says he has his own copy of the video with him at the jail, part of the disclosure he requested from police. (Usually it is defence counsel who receives the disclosure. In this case, it appears Barreira has a copy as well.)

I have not seen the video so I am not going to name the man Barreira alleges pulled the trigger.

The existence of the video is also interesting because of what it may mean for the men accused of murder.

Barreira believes it proves only one of the four is guilty, because one person pulled the trigger. Barreira says he is innocent, but was in the wrong place at the wrong time. (Selling crack cocaine, he says, to the very same co-accused he alleges shot Tyler.)

He admits to driving away in his own car with the three other accused murderers.

"Everyone runs down and hops in my Jaguar," says Barreira.

The shooter gets in and yells to him, "Yo, dog, get in the car!"

Barreira tells me the shooter fired two shots at him too, to force him into his car.

"Missed both times, thank God. I heard them hit the wall behind me. I told this to police."

Those shots, he says, were not captured on video.

When I ask Hamilton about shots fired at Barreira, he says detectives investigated all leads.

Barreira admits to being within feet of Tyler when he was shot. He admits to driving away from the scene with all of the accused in his car and admits to not reporting any of it to police.

"Yes, I'm guilty of accessory after the fact to murder," he tells me.

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I do not know if Barreira is guilty of first-degree murder. What I do know, however, is you do not have to squeeze the trigger to be found guilty of it. If you actively participate in a murder — plan it, act as a lookout, provide the weapon, drive the getaway car, for example — you can be charged with first-degree murder.

Barreira's claim is also interesting because of his past.

He admits to having a hefty criminal record: trafficking convictions for selling cocaine and weed; break-ins, possession of stolen property and possession of a firearm.

He was also charged, in 2008, with conspiracy to commit murder. He and two others were accused of plotting to kill a Hamilton man. Police stumbled on the plan while investigating the 2006 murder of Michael Walsh in a Waterdown hotel.

Barreira eventually pleaded to the lesser charge of counselling to commit murder.

Barreira was the target of a home invasion in 2006 when three men burst into his father's West Avenue house looking for drugs and money. Barreira was shot in the chest, his dad took a bullet in the leg.

Barreira says that in the hours before the invasion, he and friends were drinking at his dad's place. One of those friends was Tyler.

Everyone had cleared out by the time the invasion happened, but Tyler reappeared later that night at the hospital.

He came there, says Barreira, to watch over him.

Barreira nearly died that night.

"The bullet's still lodged in my heart," he says.

Tyler's mom calls Barreira "a scumbag liar." She insists Tyler was not there on the day of the invasion and they didn't know each other.

Barreira says he and Tyler knew each other for years. They met, he says, when he was 15, though a group of guys involved "in gang stuff." Tyler was a few years older.

"He was a Cripp," says Barreira. "He was the one we were all trying to be like ... He was a tough guy. If we were out and we got into a fight, we were going to win if Tyler was with us."

He calls Tyler "T."

Again, Tyler's mom says Barreira is lying. Her son was never in a gang. "Tyler's not here to defend himself," she says angrily.

Barreira says Tyler got out of the gang. They bumped into each other occasionally. He saw Tyler and his mom at Ikea once and had lunch with them.

Tyler's mom says that never happened.

The jail guards warn us our time is up. Barreira tells me seeing Tyler die has affected him. He has post-traumatic stress disorder and is on medication for it, he says. "I'm starting to have dreams," he says. "I see Tyler standing by my bed saying, 'Hey bro, what? You couldn't save me?'"

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