NORFOLK, Va. (AP) — A white former police officer on trial for first-degree murder in Virginia says he shot and killed an unarmed black teen after the 18-year-old knocked away his stun gun and charged toward him.

The former Portsmouth officer, Stephen Rankin, told a jury Tuesday that he was responding to a shoplifting call outside a Wal-Mart in April 2015. Rankin said William Chapman II ignored his commands and confronted him before they struggled.

While police seldom face criminal charges in shooting cases, the officer’s rare trial comes amid increasing nationwide scrutiny of police tactics and race. Rankin was fired after his murder indictment. Witnesses have offered conflicting accounts over whether Chapman charged Rankin before the shooting. A jury is expected to start deliberations this week.