(Hillsboro, OR)  --  Investigators are trying to determine what caused a crash that killed a motorcyclist in Hillsboro.  Washington County sheriff's deputies say 42-year-old Kevin Prince of Hillsboro died Tuesday night after he lost control of his motorcycle in the 25-thousand-900 block of Southwest Vanderschuere Road.  Authorities say Prince left the roadway and made impact with a guy-wire for a power pole.