Dr. Barrett Doyle Whitefield (D.O.) pleaded guilty to conspiracy to possess with intent to distribute controlled substances in the federal courthouse in midland on Thursday.
The Odessa doctor wrote prescriptions for hydrocodone to patients upon request without examinations between late 2011 and July 19, 2012.
Whitefield, 59, even wrote some prescriptions to people he didn't see as patients.
Whitefield stopped writing illegal hydrocodone prescriptions after July 19, 2012, when Drug Enforcement Administration agents and Midland Police Department Narcotics detectives executed a search warrant on his medical office in Odessa.
Whitefield also allegedly gave a packet of meth to someone in Lamesa, at the direction of others.
Prosecutors say that Whitefield even knew that some of the people he gave hydrocodone to sold the pills to others in the Midland-Odessa area.
Christina Rene Barfield, Megan Lynn Maner, Cynthia Marie Constanzo and Cody Wayne Hearn have also pleaded guilty to conspiracy to possess with intent to distribute controlled substances.
Barfield, Manter and Constanzo pleaded guilty Thursday, while Hearn pleaded guilty on January 16th.
Barfield directed others to sell hydrocodone and methamphetamine provided by the ring, while Maner and Constanzo distributed the drugs.
Hearn filled fraudulent hydrocodone and Xanax prescriptions written by Whitefield and distributed methamphetamine at the direction of Barfield.
Now, Whitefield, Barfield, Maner, Constanzo and Hearn each face at least 10 years in federal prison.
No sentencing dates have been scheduled yet.
Three other people -- Robert Michael Handlon, Matthew Christian Woodside and Amanda Leigh Glenn -- have yet to stand trial on the same conspiring to possess with intent to distribute controlled substances charges for their alleged roles in the ring.
Jury selection for the trials against Handlon, Woodside and Glenn is scheduled for 8:30 AM on February 11th.
The case was investigated by the Drug Enforcement Administration and the Midland Police Department.