Lieutenant Colonel Petrillo was commissioned through the OCC program in April 2001.
In 2002, Lieutenant Colonel Petrillo was assigned to 2nd Platoon, Charlie Company, 7th Engineer Support Battalion as a Platoon Commander. After the invasion of Iraq in 2003, Lieutenant Colonel Petrillo was selected to be the engineer detachment commander for MSSG-11, 11th MEU and deployed again to Iraq.
In 2005 Lieutenant Colonel Petrillo transferred to Recruiting Station Cleveland where he served as the Operations Officer and Executive Officer.
After recruiting duty, Lieutenant Colonel Petrillo attended Engineer Captains Career Course in Fort Leonard Wood Missouri.
In 2009 Lieutenant Colonel Petrillo transferred to 3D Combat Engineer Battalion in Twenty-Nine Palms, California and served as Alpha Company Commander and the Battalion Operations Officer where he deployed twice to Afghanistan.
In 2012 Lieutenant Colonel Petrillo attended Marine Corps Command and Staff College.
From 2013-2015 Lieutenant Colonel Petrillo served as Engineer Officer/Planner with 1st Marine Division and later as the Division Current Operations Officer.
In 2015 Lieutenant Colonel Petrillo deployed again to Iraq as part as an Advise and Assist team as the engineer.
In late 2015 Lieutenant Colonel Petrillo transferred to the 4th Marine Corps Recruiting District where he served as the Training Team Officer, Assistant for Enlisted Recruiting, Commanding Officer Recruiting Station Baltimore, and the District Operations Officer.
His personal decorations include the Meritorious Service Medal with two Gold Stars, Navy and Marine Corps Commendation Medal, and the Navy and Marine Corps Achievement Medal.