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.

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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. 

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Duff is a also a certified pistol instructor through the NRA.

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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.