Fernando Gonzales-Ramos waived his right to a preliminary hearing in federal court Tuesday.
The judge in a case ordered that Ramos stay behind bars.
According to court documents, Ramos' office in Logan County had no exam tables and no running water. Investigators say he had a pair of armed security guards at the office, and a nurse who handed out prescriptions to customers lined up at the door, ready to pay cash.
Investigators say Ramos would fill the prescriptions in Texas and travel to Logan to pass out the pills.