An airplane crash that claimed the life of a Dubuque physician who was running for the U.S. Senate on the Libertarian Party ticket was due to a loss of control, according to federal investigators.

59-year-old Dr. Doug Butzier’s plane crashed about 11 p.m. October 13, 2014 about a mile north of the Dubuque Regional Airport. He was on his way to Dubuque from Ankeny and was the only one in the plane at the time of the crash.

Butzier worked as an emergency room physician at Mercy Medical Center in Dubuque. He was running against Republican Joni Ernst, Democrat Bruce Braley, and three other candidates in Iowa’s U.S. Senate.

The National Transportation Safety Board report states investigators did not find any issues with the airplane that might have contributed to the wreck.