David Roberts, a volunteer at the Polk County Sheriff’s Office, was arrested for trafficking Oxycodone pills. (Polk County Sheriff's Office)

A volunteer at a Central Florida sheriff’s office was arrested for selling Oxycodone pills and weapons charges.

Polk deputies arrested David Roberts, 69, on Thursday, according to a press release from the Polk County Sheriff’s Office.

Investigators received a tip from an anonymous source that Roberts, of Lake Wales, receives 90 pills per month for a prescription that he sold to others. The source said they saw Roberts carrying a large amount of cash.

Deputies executed an undercover operation where they contacted him and asked to purchase the drugs, according to the press release. After buying all 90 pills, they took Roberts into custody.

Officials searched his home and found a rifle, a handgun, ammunition, a prescription pill bottle full of Oxycodone pills and a large mason jar full of a substance that tested positive for cannabis.

Roberts, a convicted felon, does not have a medical marijuana card.

He began working as a volunteer for the Polk County Sheriff’s Office in October 2009.