Lacson worked at the PC Metropolitan Command (Metrocom), Intelligence and Security Group (MISG), from 1971 to 1986. The MISG was commanded by the late Colonel Rolando Abadilla. Lacson rose through the ranks, becoming lieutenant colonel in the mid-1980s. After the 1986 People Power Revolution, he served at the PC-INP Anti-Carnapping Task Force as its commander from 1986 to 1988, as provincial commander of the Province of Isabela from 1988 to 1989, and as commander of the Cebu Metropolitan District Command (Metrodiscom) from 1989 to 1992. In 1991, he joined the then-newly created civilian Philippine National Police, or PNP, formed as a result of the merger of the military Philippine Constabulary and the civilian Integrated National Police or INP. (The INP was formed in 1975 as an integration of all local police forces in the country then under operational control of the PC.) Soon Lacson became Provincial Director of the Province of Laguna from February to July 1992. Afterwards, he was appointed Chief of Task Force Habagat at the Presidential Anti-Crime Commission from 1992 to 1995. From 1996 to April 1997, he was given the task of project officer of "Special Project Alpha." Lacson was appointed Chief of the PNP on November 18, 1999.