Police are facing mounting anger in Connecticut after they shot dead an accused teen car thief and allegedly left him handcuffed and dying on the street.

A video that appears to show 15-year-old Jayson Negron moving after he was shot by a police officer in Bridgeport has been released and family - and they say it proves cops lied about the incident.

Officers also left the teen's body uncovered in the street for hours after he allegedly rammed a cop with his 'stolen' car after a chase and then was shot.

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Negron appears to be shown in his video handcuffed and lying on Fairfield Avenue after being shot

Police confirmed Sunday they've seen the footage posted online Friday by Giovanni Rivera, who says he's the cousin of Negron who was killed by a police officer after a short chase on May 9.

Bridgeport Officer James Boulay shot Negron after cops say the teen hit the officer with a stolen car on May 9. Police pronounced Negron dead at the scene. His friend and passenger Julian Fyffe, 21, was also shot but survived.

Boulay, 30, who had no prior disciplinary record, has been placed on administrative leave pending an investigation.

The video camera pans away for four seconds and focuses on more officers arriving

When the camera pans back, Negron's head is facing the opposite direction - some believe this proves he was alive on the ground

The shaky cell phone video shows high school student Negron lying on the ground, with his arms handcuffed behind him. He doesn't appear to move.

'Yeah, they shot him. They shot that man,' says a person near the video camera.

But when the camera turns away from him and pans towards other officers arriving and it cuts back four seconds later, Negron's head is facing the opposite direction. An officer is standing near him.

'This is a nightmare. Bridgeport PD told my family they shot Jayson in the head and was dead on scene this video clearly shows otherwise,' Rivera wrote on Twitter. 'They left my baby cousin on the ground to die.'

'If that crucial part of the story is a lie, everything else is up for question,' Rivera told the Hartford Courant.

Jason Negron, 15, was a sophomore at Bunnell High School in Stratford who was shot by Bridgeport Officer James Boulay

It's unclear how Rivera obtained the video.

Autopsy results show Negron died from gunshot wounds to the chest.

Police said Negron's handcuffed body was lying in the street for several hours after the shooting for 'evidence-gathering reasons.'

He was left on Fairfield Avenue in full view for hours, a move that infuriated some locals.

Bridgeport Police Chief Armando Perez said he was told he wasn't allowed to cover the body with a sheet in case it disrupted the crime scene but later learned that the body could have been covered.

Perez said that medical personnel 'got there relatively quickly,' but did not know the exact time, according to the Connecticut Post.

Ahlaam Abduljalil, a writer and poet from Bridgeport, Conn., and a member of the Village Initiative Project, speaks to a crowd gathered for a protest and vigil for Jayson Negron on May 10

Tina Suarez, of Bridgeport, holds up a sign while attending a protest and vigil for Jayson Negron

'The callous disregard that Bridgeport police officers showed for Jayson Negron during his last moments of life is unacceptable,' David McGuire, executive director of the American Civil Liberties Union, told the outlet. 'Their behavior was outside the realms of human decency and democracy.'

Lawyer Michael Stratton, who represents the Fyffe family, also questioned the police version of how the teen came to be shot, saying there was no evidence that the car was stolen and that there were no drugs or weapons found on Negron or his friend.

'Julian was shot twice after Jayson was shot. 3 bullets,' he wrote on Twitter.

'Police cannot declare someone dead at the scene,' Stratton told Daily Mail. 'You need a doctor or medical examiner. [Police] have no legal right or expertise, nonetheless thats what happened here. They not only declared him dead, they made sure he was dead by not getting him medical care as he lay handcuffed on the ground.'

Negron was a sophomore at Bunnell High School in Stratford.

A relative described him on GoFundMe as 'a young man with a heart of gold, he had a contagious personality and no party was a party unless Jay was in it. When he came, and smiled, it was like the lights were turned on because he truly lit the room.'