Guy was a member of the New South Wales Police Force between 1979 and 2002, serving in both country and metropolitan locations. The majority of his service was in criminal investigation duties as a general investigator; however he did work in areas of specialist investigative areas such as the State Major Incident Group and was also a member of the New South Wales Crime Commission. Guy was a Negotiator with the State Protection Group for many years. Guy commenced employment with Charles Sturt University in 2007 as a lecturer in the Investigative subjects and is currently the co-ordinator of PPP122.
Guy has completed the Graduate Certificate in University Learning And Teaching (GCULT).