LINCOLN, Neb. (AP) — A Nebraska State Patrol trooper has been fired and two officers have stepped down following a probe into allegations that the agency mishandled internal investigations.

Patrol Superintendent John Bolduc announced Wednesday that one lieutenant colonel retired, one sergeant resigned and one trooper was fired. Additionally, two officers were demoted and two others received unspecified punishments. Bolduc refused to identify any of the affected employees, citing confidentiality rules.

The investigation was launched amid allegations that patrol officials failed to adequately report and handle alleged misconduct cases.

One incident involved a man who was killed when a trooper bumped his vehicle during a high-speed chase. The other involved a trooper who struck an intoxicated man in the head with a rifle butt after the man ignored orders to get on the ground.