PRINEVILLE, OR -- An Oregon State Police Trooper from Bend has been arrested and jailed on assault charges stemming from an incident last July in Powell Butte. 39-year-old Colin Tracy is accused of domestic violence towards a 39-year-old Bend woman known to him.  Detectives with the Bend Police Department have been investigating the charges for the past two weeks. When they contacted Tracy yesterday, he voluntarily turned himself in without incident. Tracy is lodged in the Crook County jail. The Crook County District Attorney’s Office will handle the case.