NORRISTOWN, Pa. (AP) — A Pennsylvania prosecutor says a fourth doctor has been arrested for unlawful prescribing and other charges as part of a months-long investigation into area physicians accused of overprescribing drugs.

Montgomery County officials along with federal Drug Enforcement Agency officers announced Wednesday that 48-year-old Lansdale physician Lawrence Miller was arrested and arraigned on 51 counts. Officials say nine of his patients had died of overdoses that often included a mix of the prescribed medication that was accompanied by little or no medical treatment and street drugs.

Court documents did not indicate whether Miller had an attorney.

Officials say the three other physicians were arrested and charged with similar counts in February, May and July. One of those physicians was prescribing medication to female patients in exchange for nude photographs or sexual favors while the others were receiving cash payments.