OKLAHOMA CITY — Oklahoma County prosecutors improperly sought conspiracy charges against a pair of former state lawmakers and don’t have adequate evidence to support the additional charges, attorneys for the lawmakers argued Thursday.

Former state Rep. Randy Terrill, R-Moore, and former state Sen. Debbe Leftwich, D-Oklahoma City, are already bound for trial on felony bribery charges on what prosecutors allege was a scheme give Leftwich an $80,000-a-year state job so a Republican colleague of Terrill’s could run for her open seat.

But at the conclusion of last year’s preliminary hearing, Oklahoma County prosecutors sought to add the additional charge of conspiracy against the two lawmakers. The judges denied the request, ruling there was insufficient evidence to authorize the conspiracy charge. District Judge Ray Elliot also cited a legal guideline, known as Wharton’s rule, which prevents fewer than three people from being charged with conspiracy in certain cases.

On Thursday, the judges on the five-member Oklahoma Court of Criminal Appeals questioned why prosecutors didn’t file formal conspiracy charges that outlined the details of the alleged crime.

Judge Gary Lumpkin asked First Assistant District Attorney Scott Rowland how he could argue that the lower-court judge erred in his ruling when it has never been alleged “with enough specificity to determine if a charge should be filed.”

Rowand responded: “It’s cumbersome in its current posture, I admit.”

Rowland said after Thursday’s hearing that it’s common practice in Oklahoma County for prosecutors to ask at the end of a preliminary hearing for an additional charge and then file the written information later.

Terrill said after the hearing he believes the appellate court will reject prosecutors’ attempt to add the conspiracy charges.

“Obviously the lower court has tossed these particular allegations out on not one, but two different occasions, and both I and my legal team think that’s going to be the end result of this opinion,” Terrill said.

Terrill also complained about the amount of time it’s taken for the case to proceed, since charges were initially filed in 2010.

“Complex murder cases are handled in less time than this,” he said.

Despite the pending investigation into the alleged corruption, Terrill and Christian both were reelected to their House seats in 2010. Leftwich didn’t seek re-election. In 2012, Terrill ran unsuccessfully for Cleveland County commissioner. Christian was again reelected to his House seat in south Oklahoma City.