WICHITA, Kan. (AP) — A physician accused of operating a "pill mill" was charged Thursday with illegally prescribing drugs in incidents that prosecutors say caused the overdose deaths of at least four patients.

A Topeka grand jury returned a 34-count indictment against Dr. Stephen J. Schneider and his wife, nurse Linda K. Schneider, who were arrested Wednesday, U.S. Attorney Eric Melgren said. They are to appear in federal court in Wichita on counts including conspiracy, unlawful distribution of a controlled substance, health-care fraud, illegal monetary transactions and money laundering.

According to the indictment, 56 of the doctor's patients have died from accidental prescription drug overdoses in the past five years. However, the indictment said only four of the deaths were found to be directly caused by drugs prescribed by Schneider's clinic in Haysville, south of Wichita.

The Schneiders are not charged with killing any patients.