Authorities have identified the two men killed in a helicopter crash March 31st in Audubon County. Officials said helicopter passenger 23-year-old Des Moines resident Benjamin Peterson and the pilot, 30-year-old Minneapolis resident Ryan Doolittle of Minneapolis both died in the crash. Peterson worked as an aerial wildlife surveyor. The crash happened in Audubon County, just a few miles east of Hamlin. Authorities said the aircraft hit a power line before it went down.The crash is still being investigated by the National Transportation Safety Board and the FAA.