Dr. Stephen Mackenzie has been training and working police service dogs for over 17 years. He is a part time Deputy with the Schoharie County Sheriff's Office (New York).  During his law enforcement career he has served as a K-9 handler for 7 years and K-9 Trainer for 8 years. Stephen Mackenzie is a Trainer/Examiner of police dog teams for the state of New York; an Examiner of police work dog teams for the Connecticut Police Work Dog Association; and a Master Trainer with the North American Police Work Dog Association.

Dr. Stephen Mackenzie originated the K9 column in Police Magazine and served as a Contributing Editor on police dogs for Dog Sports Magazine for 11 years before writing Decoys and Aggression: A Police K-9 Training Manual. An animal behaviorist, he holds a doctorate in the genetics of animal behavior from Cornell University and is presently a Professor of Animal Science for the State University of New York.

According to the book description of Decoys and Aggression: A Police K-9 Training Manual “A good decoy needs to be an expert in canine communication, and needs to know how to use this language to stimulate aggression in the dog. This book explains, step by step, how to understand the canine paralanguage and how to use your own body to communicate with the dog. It then explains the different types of natural dog aggression and how to use its own language to trigger the useful types without being abusive to the dog. Decoys and Aggression also describes drills designed to develop skill in the decoy. Some are designed to be conducted without dogs until the human demonstrates enough body control to work with a live animal without injuring the dog or himself. This book is the first to combine inter-species communication skills with the specific types of aggression known to be useful to police dog trainers. As such, it is essential reading for all decoys, instructors and students alike, as well as for K9 personnel, handlers, and trainers.”