POMONA— A member of the Mongols motorcycle gang who shot and killed a Pomona police officer in 2014 was sentenced Tuesday to 10 years in prison.

David Martinez, 44, was sentenced for voluntary manslaughter for the October 2014 slaying of Shaun Diamond.

Diamond, 45, was a SWAT team member who was taking part in a multi-agency operation targeting the Mongols. He was helping execute a search warrant at the San Gabriel home where Diamond lived with parents, sister, girlfriend, and two children.

Officers had been forcing their way into the home when Martinez fired a shotgun. The blast struck Diamond in the back of the neck, severing his spine. He was removed from life support a day later.

Martinez surrendered to authorities shortly after the shooting. Martinez said he didn’t hear the SWAT officers identify themselves and thought his fellow Mongols were coming for him because he had wanted to quit the gang.

Martinez said he was only trying to protect his family and called the shooting an accident.

Prosecutors said Martinez was lying and had never intended to leave the Mongols.

In two previous trials, jurors acquitted Martinez of first-degree murder and second-degree murder. But in November, he pleaded no contest to voluntary manslaughter and assault with a firearm on a police officer.

Because he already has spent more than eight years behind bars, Martinez could be released as early as March.