An investigation is underway after a Platteville man died in a helicopter crash in Oshkosh.  Authorities say the helicopter hit power lines Saturday and went down in the Fox River.  The Winnebago County Sheriff’s Office has identified the victim as 27-year-old Jonathan Bahr. His body was recovered by divers Saturday night.  Authorities believe he was the only occupant of the helicopter.  Because the power lines fell into the water, rescue efforts were delayed for about two hours while the lines were secured. Sheriff’s officials say boat traffic along the Fox River was shut down for about nine hours while the helicopter was removed from the river and the power lines repaired. The investigation has been turned over to the N-T-S-B and the F-A-A.