RIVERSIDE, Calif. (AP) – A doctor’s assistant in San Bernardino County has pleaded guilty to writing and selling prescriptions for addictive painkillers to people he did not examine.

The U.S. attorney’s office said Friday that 50-year-old Christopher Lister admitted in a plea agreement that he wrote prescriptions for oxycodone without a legitimate medical purpose. The Apple Valley man had a mobile medical service that operated throughout the county.

Prosecutors said Lister sold the prescriptions for cash to buyers who obtained the painkillers and then resold some of the drugs to others.  Lister faces up to 20 years in prison, probation for the rest of his life and up to $1 million in fines when he is sentenced Feb. 25.