White Chicago cop Jason Van Dyke says Lacquan McDonald was 'bugging out' before ...

The white Chicago police officer who shot dead black teenager Laquan McDonald in 2014 claimed on Tuesday that the 17-year-old was 'bugging out of his head' when he shot him 16 times. 

Jason Van Dyke, 40, finally took to the stand in his long-awaited murder trial in Chicago on Tuesday to defend killing the teenager four years ago in a crime which fueled racial debate and anger over police treatment of black men across America. 

He claimed that McDonald, who had been reported to police for breaking into a truck, stared at him vacantly moments before he opened fire. 

Painting the teenager as unpredictable and dangerous, he said through tears: 'His eyes were just bugging out of his head. 

'He had just these huge white eyes just staring right through me.' 

Later, he said dashcam footage which showed him shooting the teenager even as he lay on the ground 'does not show his perspective'. 

He also said he thought he was 'backpedaling' when he was seen walking towards the teenager. 

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Jason Van Dyke, 40, wept at times on the witness stand on Tuesday as he recalled shooting dead black teenager Laquan McDonald in 2014. He claimed McDonald was 'bugging out' and had 'huge white eyes' at the time

Jason Van Dyke, 40, wept at times on the witness stand on Tuesday as he recalled shooting dead black teenager Laquan McDonald in 2014. He claimed McDonald was 'bugging out' and had 'huge white eyes' at the time

Jason Van Dyke, 40, wept at times on the witness stand on Tuesday as he recalled shooting dead black teenager Laquan McDonald in 2014. He claimed McDonald was 'bugging out' and had 'huge white eyes' at the time

'He waved his knife from his lower left side upwards, across his body towards my left shoulder.  

Making repeated mention of the teenager's hoodie, he then admitted to shooting at his knife as he was lying on the ground after being hit.

Laquan McDonald was 17 at the time. He had been reported to police for stealing vans. Van Dyke and another officer who responded to the scene both described him as behaving in a 'deranged' way 

Laquan McDonald was 17 at the time. He had been reported to police for stealing vans. Van Dyke and another officer who responded to the scene both described him as behaving in a 'deranged' way 

'All I could see was him starting to push up with his left hand off the ground.  

'I still see him holding his knife in his right hand, eyes still bugging out of his face, still showing no expression.

'I just kept on looking at the knife and I shot at it. I just wanted him to get rid of that knife,' he said. 

Earlier, a psychologist testified that Van Dyke told him after the shooting how he believed he would 'have to' shoot the teenager before even arriving at the crime scene.

Dr. Laurence Miller told the court Van Dyke had told him that he had told his

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