Oklahoma - An Oklahoma Highway Patrol Captain accused of trying to blackmail the head of the OHP is denying the allegations.

Troy German has pleaded not guilty to an extortion charge.

He's accused of trying to blackmail State Department of Public Safety Commissioner Rusty Rhoades.

Court documents show German threatened to release evidence of OHP misconduct if Rhoades rejected German's request for a promotion.

A grand jury indicted him Thursday. He entered his plea on Friday and bonded out of jail.

Defense attorney Mike Johnson told The Oklahoman German "100 percent" denies the allegation. He also called German a "whistleblower" who exposed high level corruption within the Highway Patrol. 

DPS responded by saying there had been an internal investigation into German and his claims. The department also said it "fully supported the decision to escalate the matter to the grand jury."

German's preliminary hearing is set for March.