Frigulti is a U.S. Marine Corps combat veteran who served as an infantry platoon and company commander in Vietnam. He served on the Los Angeles FBI SWAT team for 15 years as a sniper, sniper team leader, and assault team leader. He was the principal firearms instructor for the Los Angeles field office for 17 years until his retirement. Frigulti directed the FBI's Police Training Unit in Los Angeles responsible for the tactical and firearms training of agents, as well as instructing local law enforcement and the military. In 1996, he was certified by the FBI as a Master Police Instructor. He is also a California-certified P.O.S.T. Police Instructor and NRA Police Firearms Instructor. Upon retirement, he has continued to provide training to law enforcement and military personnel through is company Police Training Consultants (PTC).