(Reuters) - A jury convicted a former Portsmouth, Virginia, police officer of voluntary manslaughter on Thursday for the shooting death of an unarmed black teenager last year, a court spokeswoman said.

The ex-officer, Stephen Rankin, 36, had been charged with shooting William Chapman II, 18, in April 2015 while investigating a shoplifting report at a Walmart.

Rankin, who faces up to 10 years in prison, was fired by the police department after his grand jury indictment.

The conviction in Portsmouth Circuit Court comes amid a roiling U.S. debate over police use of deadly force, especially against African-Americans.

Prosecutors had charged Rankin, who is white, with first-degree murder and a weapons violation. The jury comprising eight African-Americans and four whites found him guilty of the lesser manslaughter charge, the spokeswoman said.

Prosecutors argued that Rankin killed Chapman in what had amounted to little more than a fist fight in a Walmart parking lot in Portsmouth, about 175 miles south of Washington.

Rankin testified that Chapman repeatedly ignored his commands and when he tried to handcuff him he attempted to escape.

He said Chapman knocked a Taser out of his hands and charged at him before he fired. Chapman was shot once in the face and in the chest and was pronounced dead at the scene.

(Reporting by Ian Simpson in Washington; Editing by Sandra Maler)