Raised in Simi Valley, California, Captain John McMahon was originally inspired to join the Department by his father, a World War II Army veteran, who greatly admired the Los Angeles Police
Department. In 1989, Captain McMahon graduated from the police academy and later from the University of LaVerne with a BA in Business Administration. Captain McMahon is also a graduate of the West Point Leadership Academy.
As a police officer, Captain McMahon worked a variety of patrol assignments, which included assignments as an undercover narcotics officer, gang investigator, staff writer and a Senior Lead
He was promoted to sergeant in 1996. In addition to being a field supervisor, he served as an Assistant Watch Commander to patrol operations at Wilshire Area, supervised a staff responsible for
preparing directives regarding Department policy and procedures for the Chief of Police and was also assigned to Internal Affairs as a member of the Rampart Corruption Task Force.
He was promoted to lieutenant in 2001. In his twelve years as a lieutenant, he has worked as a watch commander, administrative lieutenant, detective commanding officer, and as the Officer in
Charge when Operations-Valley Bureau first implemented it’s Violent Crime Task Force. It was this task force that, under his leadership, received great accolades and positive publicity for exceptional productivity and the noteworthy number of high-profile arrests along with a significant amount of gun and narcotics seizures. He went on to Central Area and became the Gang Impact Team Officer in Charge. In his four years, this group consistently led the City in narcotics arrests.
Prior to his promotion to captain, McMahon was the adjutant to the Commanding Officer, Counter-Terrorism and Special Operations Bureau (CTSOB). In this assignment, he provided support to the commanding officer’s oversight to the bureau’s five divisions: Metropolitan, Major Crimes, Air Support, Emergency Operations and Emergency Services. This assignment has given him the opportunity to travel to Abu Dhabi and Dubai to showcase to this region of the Middle East, the Department’s counter-terrorism capacities and capabilities.