A judge in New Orleans has told prosecutors that they should either file charges against a Louisiana State University doctor and two nurses accused of killing patients in the aftermath of Hurricane Katrina, or exonerate the three people, the Associated Press reported.

Anna Maria Pou, an associate professor, and two nurses not affiliated with the university were arrested in July and later released. The women, who were accused of administering fatal doses of painkillers to four severely ill patients in the flooded and sweltering university hospital, have not been indicted. Their lawyers maintain they are innocent and did all they could for their patients in the deteriorating conditions at the hospital.

A spokesman for the district attorney’s office said that a grand jury would be convened early next year and that he did not want to be hurried by the court.