TULSA, Okla. (AP) — Attorneys for a Tulsa police officer charged with manslaughter in the fatal shooting of an unarmed man say a police homicide sergeant told the prosecutor that the case was "unwinnable."

Attorneys for 42-year-old Betty Shelby on Wednesday asked a district judge to dismiss the charge against Shelby and filed a motion saying Sgt. Dave Walker told District Attorney Steve Kunzweiler "that he filed an unwinnable case" and there was no probable cause for the charge.

Shelby is charged in the Sept. 16 shooting death of 40-year-old Terence Crutcher.

Kunzweiler told the Tulsa World that his response to the motion will "take issue" with how the evidence is characterized.

Walker declined comment.

Shelby was ordered on Nov. 29 to stand trial on the charge and arraignment is set for Feb. 1