Oregon State Police have arrested a Seattle man after a traffic stop near Ashland led a trooper to find 13 ounces of cocaine. State Police say the trooper stopped the car Tuesday on Interstate 5 because the passenger wasn't wearing a seat belt. The investigation led the trooper to find 13 ounces of cocaine with an estimated value of about $8,000. State police said 46-year-old Gerald Keith Riggins was arrested for investigation of possession, delivery and manufacture of cocaine. The male passenger was cited for possession of a small amount of marijuana.