The lawyer for a white Chicago police officer charged in the 2014 murder of a black teenager said on Wednesday his client feared for his life and that dashboard camera footage released by police is unreliable because video “distorts images.”

Daniel Herbert told CNN that Officer Jason Van Dyke arrived at the scene 18 minutes after a suspect carrying a knife was reported to have threatened businesses and vandalized police cruisers. Prosecutors said Van Dyke shot 17-year-old Laquan McDonald 16 times only 30 seconds after he arrived.

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“The reason my client Jason fired his weapon that evening back in October 2014 is that he truly was in fear for his life as well as the lives of his fellow police officers,” Herbert said.

The Chicago shooting charges followed more than a year of unrest across the United States over police shootings of black men that was sparked after the August 2014 killing of unarmed Michael Brown, 18, in Ferguson, Missouri.

The video of the McDonald shooting, shot by a camera mounted on the dashboard of a police car and made public on Tuesday under orders from a judge, prompted mostly peaceful street demonstrations in Chicago. Van Dyke, the first Chicago police officer to face a murder charge for an on-duty incident in decades, was charged hours before the video was released.

Authorities said McDonald was carrying a pocket knife and had the hallucinogenic drug PCP in his system when he was killed.

Prosecutors said Van Dyke fired the 16 shots within 30 seconds of arriving and just six seconds after emerging from his patrol car, emptying his gun at McDonald and preparing to reload. Herbert told CNN his client was afraid McDonald was going to attack him with a knife.

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Herbert said the video was not an indicator of his client’s guilt.

“Video by its nature is 2-dimensional. It distorts images. So what appears to be clear on a video sometimes is not always that clear,” Herbert said.

The release of the video itself has been controversial.

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Civil rights activist Al Sharpton criticized Chicago city officials for blocking the video, which was made public only after an independent journalist filed a Freedom of Information Act lawsuit.

Sharpton, speaking on MSNBC’s “Morning Joe” program, called for a special prosecutor to handle the case “because the politics here needs to be investigated.”

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The Chicago Police Department had argued that releasing the video would taint multiple investigations.

“Investigations of police shootings and misconduct are highly complex matters that carry with them very unique legal issues, that must be fully examined and taken into consideration,” Cook County prosecutor Anita Alvarez said on Tuesday.

Republican presidential candidate Jeb Bush, appearing on CNN, said rising violence in big cities makes it hard to be a police officer. However, Bush said, “When they do what appears to have happened here they should be charged as was the case in this case.”

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(Additional reporting by Fiona Ortiz in Chicago and Susan Heavey in Washington; Editing by Bill Trott)

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