A key witness took the stand today in the trial of former Minneapolis police officer Mohamed Noor, who shot and killed Justine Damond in July 2017 after she called 911 to report a possible assault outside her South Minneapolis home.

A teenager–who was 16 at the time of the incident–was riding his bike to a friend’s house that night when he noticed police parked near an alley. The teen said he was trying to keep a low profile because he had been drinking and had marijuana with him. He says that as he rode by, he heard a gunshot and decided to stop and pull out his cellphone to record what he was seeing. That’s when he noticed a woman on the ground–Damond–and one of the officers rushing toward her. Noor claims the shooting was in self-defense.