Dr. Robert Rand, the doctor at the center of an alleged illegal pill ring, is scheduled to enter a plea in federal court this afternoon. A federal investigation into a prescription drug-trafficking ring in Reno is the most extensive in the state to date. But U.S. Attorney Daniel Bogden says it’s just one in a series his office and others have uncovered since they stepped up efforts in recent years to combat the growth of what he calls “dirty doctors and illicit pill mills.” During the last 18 months, four Las Vegas doctors have been convicted and sentenced to prison for illegally distributing painkillers.