Duff has been a Nebraska State Trooper for 28 years and just retired August 2, 2019. He has been a range instructor for the Nebraska State Patrol for 8 years.
He has also been a Defensive Tactics Instructor for 27 years. This includes Pressure Points and Control Tactics, hand-to-hand fighting, weapon retention, strikes and kicks, and spontaneous knife fighting.
Duff is a also a certified pistol instructor through the NRA.
He has been an avid hunter and shooter since he was young. He has raised and trained pointing dogs for over 30 years and has recently taken up bow hunting.