John Kelly is a renowned criminal profiler, psychotherapist, and addiction specialist. In his 1992 paper, "The Alcohol, Drug, and Serial Killer Connection", he was the first theorist to label serial killing as an addiction. Kelly's profiling expertise was used in over 100 cases, including well-known cases such as the Green River Killer, the Molly Bish case, the Atlantic City Murders, the Woodsman of Worcester, and the Golden State Killer.

His efforts as a profiler have led to three appearances on CBS 48 Hours and multiple interviews on CNN Primetime with Nancy Grace, FOX-Geraldo at Large, NJ Channel 12, and HLN-Jane Velez-Mitchell Show. Also, in the three-season television show "Dark Minds" on the Investigation Discovery channel, Kelly was seen around the world in 22 episodes over a three-year span.

He was also the founder of S.T.A.L.K., Inc. (System to Apprehend Lethal Killers) and the Executive Director of ExtraCare Health Services LLC, an outpatient counseling agency for mental health and addictive illness. He is a board Certified Forensic Examiner, a Fellow of the American Board of Forensic Examiners, and a National Certified Addiction Specialist. Kelly is also a published author who wrote the book "Warning Signs - A Guidebook for Parents", and he will be releasing a second book called "Finding Lazarus".