Duncan has lived in Clark County most of his life. He started at the Sheriff’s Office as a Cadet in 1989. He then started his law enforcement career as a Reserve Deputy Sheriff before being hired full-time in 1991 as a Deputy Sheriff.   

During his 33-year law enforcement career, Duncan held the position of Patrol Deputy for his first 17 years. In 2005, he was promoted to Sergeant where he supervised a patrol squad for two years before taking over as the Tactical Detective Unit Supervisor. During his time as Sergeant, he was awarded Supervisor of the Year on two separate occasions. After leaving the Tactical Detective Unit, he supervised the Major Crimes Unit before being promoted to Commander in 2018.  As a Commander he directed patrol operations and special events before being assigned to the position of Investigative Commander. In this position he was responsible for the Major Crimes Unit, Drug Task Force, Children’s Justice Center, along with the Air Support Unit and the Regional Independent Investigative Team.

Duncan earned a Bachelor of Science degree in Criminal Justice from Aspen University and also holds a Master of Science degree from Western Governors University in Management and Leadership.  

Duncan and his wife have one daughter. He enjoys traveling, camping, flying airplanes and playing golf.