OKLAHOMA COUNTY - A former investigator with the Oklahoma County District Attorney’s Office is planning to sue, saying he was fired because he refused to help the district attorney illegally target political rivals. 

The filings suggest DA David Prater not only misused his power, but also may have broken the law.

Former investigator William Muller said DA Prater ordered him to dig up dirt on the group “Oklahomans for Criminal Justice Reform,” using a multi-county subpoena prater illegally obtained to seek financial records. 

According to the filing, “David Prater…without any known ‘probable cause’…ordered Mr. Muller to obtain a Multi-County Grand Jury Subpoena…to obtain the banking and financial records…for the organization Oklahomans for Criminal Justice Reform.”

“You have to have probable cause to use a grand jury subpoena to do so. In this case, no investigative agency, no open file, no one else. Just Mr. Prater,” said Muller’s attorney, Robert Gifford.

When Muller couldn’t find any wrongdoing by Oklahomans for Criminal Justice Reform, he said the DA “…immediately became irrational and angry.” Also, that Muller, “…was becoming the target of Mr. Prater’s hostility and outrage.”

“He was escorted out the door after being berated, and to this day has never been told for the reason that he was fired,” said Gifford.

Now Gifford said he was forced to send a cease and desist letter to DA Prater because, he said, now DA Prater is illegally using taxpayers’ dollars to harass a former co-worker of Mullers, trying to dig up dirt on him.

“It’s inappropriate that the DA’s office would use law enforcement resources, taxpayer resources, to go out and seek dirt on Mr. Muller,” said Gifford.

The DA has six months to respond to the notice of claim.

News 9 did reach out to both DA Prater and his office. Neither have responded to a request for a comment.