Former FBI Special Agent, polygraph examiner and friend to Dr. Phil, John R. “Jack” Trimarco has died.

A frequent guest and contributor to Dr. Phil, Jack Trimarco served as a Special Agent for the FBI. including program manager for the FBI Polygraph Unit at the Los Angeles Field Office from 1990 until his retirement in 1998. He also served as Inspector General for the United States Department of Energy Polygraph Program between 2000 and 2002. Following his training with the Department of Defense and the FBI as a polygraph lie detection expert, Jack conducted more than 3,500 polygraph tests during his career.

“I always said he was the best of the best and his absence will be felt deeply because no one will ever be able to fill his shoes,” says Dr. Phil on Wednesday’s episode, adding, “You all saw the extremely professional side of him working diligently to help our guests and get to the truth. But we knew another side of this kind, funny and gentle man.”

Jack Trimarco is survived by his wife, Nora; three daughters, Chris, Sharon and Stephanie; and two granddaughters, Katelyn and Karly.

Watch the video above for a special tribute from the producers and staff at Dr. Phil.