COLUMBUS, Ohio (AP) — Lawyers for the Ohio hospital doctor charged with murder in 25 patient deaths accused the prosecutor of misconduct and asked Tuesday that the court dismiss the indictment handed up by a grand jury.

Former intensive care doctor William Husel is accused of ordering excessive painkillers for patients who died shortly thereafter in the Columbus-area Mount Carmel Health System. Prosecutors charged him only in cases involving at least 500 micrograms of fentanyl, saying doses that big in nonsurgical situations pointed to an intent to prematurely snuff out lives.

Husel's lawyers argue that Franklin County Prosecutor Ron O'Brien wrongly influenced the grand jury and prejudiced Husel by excluding information about a patient who received even larger dosages — a total of 2,500 micrograms of fentanyl plus 16 micrograms of hydromorphone in a 37-minute span — and survived for 10 days afterward, eventually dying with no trace of fentanyl in her system.

O'Brien didn't seek an indictment in that death “because he knew that presenting that evidence to the grand jury would reveal the truth — that 500 micrograms of fentanyl is not a ‘lethal dose,' and that administering such a dose does not indicate an intent to cause or hasten death,” the defense attorneys wrote in the court filing. They also requested a copy of the transcript of the grand jury proceedings, which are generally secret.

A statement from O'Brien said his office is reviewing the matter and will file a response in court.

Husel, 44, previously pleaded not guilty and maintains he was providing comfort care for dying patients, not trying to kill them. His defense team includes Jose Baez, the Florida-based attorney known for successfully defending high-profile clients such as Casey Anthony and Aaron Hernandez.

The case is one of the biggest of its kind ever brought against an American health care professional.

Mount Carmel's review concluded Husel ordered excessive painkillers for about three dozen patients who died over several years. Colleagues who administered the medication weren't criminally charged, but the hospital system said it fired 23 nurses, pharmacists and managers after its internal investigation and referred various employees to their respective state boards for review and possible disciplinary action.

Mount Carmel also has made changes in its operations and reached related settlements totaling more than $16.7 million over the deaths of at least 17 patients. More lawsuits by patients' families remain pending.

Husel and some of his former colleagues also filed defamation cases that accuse Mount Carmel of spreading a false narrative about what happened. Mount Carmel denies that and has stood by the findings of its review.