TULSA, Okla. (AP) - Prosecutors are asking a judge to delay the trial of a former Oklahoma reserve deputy who fatally shot an unarmed man, saying they need more time to prepare for expert witnesses the man's defense attorneys intend to call.

The ex-Tulsa County Sheriff's Office volunteer, Robert Bates, is scheduled to go on trial April 18 for second-degree manslaughter. Bates has pleaded not guilty and says he confused his stun gun and handgun when he fatally shot Eric Harris.

A judge could decide the request on Tuesday.

Shortly after Harris was killed, an attorney for the victim's family released a 2009 internal office memo questioning Bates' qualifications to be a reserve deputy.

The memo alleged superiors knew that Bates didn't have enough training but pressured others to look the other way.