Wichita ? Lawyers for a Kansas doctor charged with illegally prescribing narcotic painkillers linked to 58 accidental overdose deaths want a federal prosecutor and an investigator removed from the case.

The defense filed a motion Monday in federal court contending that the prosecutor and investigator violated professional ethics by improperly contacting defense expert witnesses and lying to the court.

The motion also seeks a protective order from any such actions in the future and asks the court for an evidentiary hearing or sworn depositions to investigate the alleged incidents.

Dr. Stephen Schneider and his wife, nurse Linda Schneider, are charged in a 34-count indictment with directly causing four deaths and contributing to 21 deaths.

Lawrence Williamson, the attorney representing the doctor, said the defense wants Assistant U.S. Attorney Tanya Treadway and investigator James Greer disqualified from the case. Greer is a special agent with the Department of Health and Human Service’s Office of Inspector General.

The U.S. attorney’s office said it will file its response to the court. Jim Cross, spokesman for U.S. Attorney Eric Melgren, also said in an e-mail that “the judge has not yet had an opportunity to review the defense’s allegations and to weigh their credibility.”

Monday’s court filing is the latest salvo in an acrimonious case marked by escalating personal attacks lobbied by attorneys on both sides against each other. The government has also tried on three separate occasions to remove some or all the defense attorneys.

The Schneiders are charged with conspiracy, unlawful distribution of controlled substances, unlawful distribution of a controlled substance resulting in death, health care fraud, health care fraud resulting in death and illegal monetary transactions. Prosecutors are also seeking the forfeiture of assets.

“The government agents responsible for the prosecution of this case have abdicated their duty to seek truth and justice, and have instead focused their efforts at winning at all costs, and using all of the power and resources of the United States government to do so,” the defense motion said.