Deputy Chief Guerrera began his law enforcement career in 1988, as a patrol officer with the Cornell University Police Department, where he attended the Broome County Law Enforcement Academy in 1990. In March of 1993, DC. Guerrera accepted a position with the Cortland City Police and graduated from the Onondaga County Law Enforcement Academy in 1994.

As a patrolman, DC. Guerrera was active in community policing and became one of the department’s first certified Bicycle Patrol Officers. In May 1999, he was promoted to the rank of Uniform Sergeant, where he oversaw patrol operations, until his assignment to the department’s Youth Division in May 2008. DC. Guerrera obtained his New York State certification as a Juvenile Officer and continued to receive training in criminal investigations surrounding children. In August 2009, DC. Guerrera was promoted to oversee the operations of the Detective Bureau, and became the new Public Information Officer for the department. While directing the Detective Bureau DC Guerrera was involved in the Cortland County Drug Task Force and the Counter Terrorism Task Force, managed case assignments and criminal investigations, oversaw the youth division and the custody and control of property and evidence, and maintained the budget and scheduling of detectives.

In August 2010, DC. Guerrera accepted the position of Uniform Lieutenant, where he oversaw the daily operations of the uniform patrol division. In this position DC. Guerrera was responsible for: supervising patrol sergeants; managing: scheduling, record management system, crisis intervention team, training division, tactical team, canine program, social media, community policing, impound parking lot, bicycle patrol unit, new employee orientation, internships, civilian ride-a-longs, parking enforcement division, filed training, accreditation, hostage negotiators, federal forfeitures, and performance evaluations; overseeing reviewing committees for use of force, motor vehicle crashes, pursuits, and recognition and awards; liaison to 911 center, police academy, information technology, traffic safety, Stop DWI, mental health association, chemical dependency committee, sequential intercept committee, and suicide prevention committee; programming and management of surveillance camera system, scheduling software, mobile video system, Livescan system, telephone system, telephone recording, computer systems, mobile computer system, and computer network; critical incident commander; City's Blood borne Pathogens co-coordinator.

In 2011, he graduated the 220th Session of the FBI National Academy in Quantico, Virginia and is a member if the FBINA Associates

In 2013 DC Guerrera formed the department's Crisis Intervention Team in collaboration with several community service organizations. The CIT is a team of volunteer officers who receive 40 hours of specialized training to deal with person in crisis or otherwise emotionally disturbed in a variety of situations in the Cortland community.

DC. Guerrera was a lifelong resident of Elmira, New York, where he graduated from Elmira Southside High School in 1984. He continued his education at Mansfield University in Pennsylvania, where he graduated with a BA in Criminal Justice Administration in 1988. DC. Guerrera relocated to the Cortland area in 1991. DC. Guerrera is a member of the Cortland County Enhanced Multidisciplinary Task Force, the Zone 6 Counter Terrorism Task Force. He also sits on the following County committees: traffic safety, Emergency Planning, Mental Health Subcommittee and the Chemical Dependency subcommittee.