'I just wanted him to get rid of that knife': Van Dyke testifies at murder trial

CHICAGO (AP) - A white Chicago police officer charged with murder in the shooting of Laquan McDonald testified Tuesday that he opened fire when the black teenager kept "advancing" at him waiving a knife.

Officer Jason Van Dyke said he kept firing because he was not certain that he had struck the teen until the teen fell to the ground. Video of the shooting shows McDonald veering away from officers when Van Dyke opens fire. McDonald spins and crumples to the ground as Van Dyke continues to fire. He fired 16 shots at the 17-year-old.

Van Dyke at times became emotional and wiped tears from his cheeks during his testimony. In a clear but sometimes halting voice, he said McDonald never let go of the knife even after the teen fell to the ground. Van Dyke said that to this day he can still see McDonald holding the knife, saying, "I just wanted him to get rid of that knife."

McDonald was shot after police were called to a report of someone breaking into vehicles. Testimony and video show responding officers called for help and were waiting for someone to arrive with a Taser.

Lawyers for clients who aren't police officers typically advise against testifying because it opens them up to potentially devastating cross-examination. But it's not obvious whether the right legal strategy for officers, like Van Dyke, is to stay off the witness stand.

Van Dyke took the stand after a psychologist testified that he believed that when Van Dyke fired his weapon it was a "reasonable response" to what he perceived as a deadly threat posed by McDonald.

Dr. Laurence Miller interviewed Van Dyke for the defense. He said the officer told him that before he got out of his squad car, he had told his partner they would have to shoot the black teenager and wondered why officers had not already done so.

While it was unclear whether the testimony helped or hurt Van Dyke's case, the jury now has testimony that Van Dyke was at least considering on the night of Oct. 20, 2014, that he'd have to shoot the teen even before he got out of his squad car.

"He told his partner, 'Oh my God, we're going to have to shoot this guy,'" said Miller, who testified that Van Dyke on the way to the scene was learning over his radio that the teenager had stabbed a tire of a police cruiser. And, said Miller, he wondered aloud, "Why didn't they shoot him if he's attacking them?"