(CNN) Chicago police officer Jason Van Dyke, who is accused of killing 17-year-old Laquan McDonald, took the stand Tuesday in his murder trial.
Van Dyke faces two counts of first-degree murder, 16 counts of aggravated battery and one count of official misconduct in McDonald's death
Here are several takeaways from Van Dyke's testimony:
Van Dyke testified McDonald "turned his torso towards him" and raised the knife across his body. At that point, he shot him, Van Dyke said.
But Prosecutor Jody Gleason challenged Van Dyke's account, pointing out one of several inconsistencies in his testimony.
"You've sat here for several days and watched several videos. ... Have you ever seen Laquan McDonald do that on one of those videos?" Gleason asked.
She showed Van Dyke the infamous dashcam video of the shooting and an animated re-creation. McDonald contended the videos didn't show his perspective.
The animated re-creation "was not from eye level," he told Gleason. "It's not showing what I saw. It's showing the back of my head and above me."
Van Dyke later acknowledged he didn't see McDonald raising the knife in the animated video.
Prosecutors have said Van Dyke unnecessarily fired 16 times at McDonald six seconds after the officer arrived on the scene that night in October 2014.
Van Dyke, who is white, said when he jumped out of his patrol car, he saw McDonald's face was "expressionless and he noticed McDonald's eyes.
"His eyes were just bugging out of his head," Van Dyke said. "He had these huge eyes, just staring right through me."
Van Dyke said he kept telling McDonald to drop the knife.
Gleason asked Van Dyke if he managed to see McDonald's "bugged out eyes" in the six seconds before he opened fire.
"Yeah, I saw his eyes," Van Dyke said.
Van Dyke testified that he stopped shooting when he recognized McDonald had dropped to the ground and then approached him.
He saw McDonald "starting to push up with his left hand off the ground," Van Dyke said.
"I see his left shoulder start to come up. I still see him holding that knife with his right hand, not letting go of it," he said.
Gleason asked Van Dyke to point out where in the dash cam video McDonald can be seen trying to get up off the ground after he was shot.
The video does not show that.
"From that video, it may not show it, but that wasn't from perspective," he said. "I was coming at a completely different angle."
Van Dyke said he ordered McDonald to drop the knife multiple times, but he refused even as he lay on the ground.
During cross examination, Van Dyke acknowledged that he was trained to shoot at the center mass of a person's chest, which is the target they are most likely to hit.
"So, why would you continue to shoot at his knife? That's not what you're trained to do," Gleason said.
"My focus was just on that knife, and I just wanted him to get rid of that knife," Van Dyke said. "That is all I could think."