LEXINGTON, Neb. (AP) – A 33-year-old Lexington man convicted on a drug charge has been given 15 years in federal prison. A news release from the U.S. Attorney’s Office says Melvin Vaughn had pleaded guilty to conspiracy to distribute more than 280 grams of cocaine base. He was sentenced on Wednesday by U.S. District Judge Richard Kopf. Vaughn must serve five years of supervised release after he gets out of prison.