Lieutenant Colonel Diener is a native of Los Angeles, California. He enlisted in the Colorado Army National Guard in May 2003 and served as a Multiple-Launch Rocket System Crewmember until his acceptance into the PLC-Combined program. He completed OCS in the summer of 2005, and was commissioned in December 2005 after graduating from the University of Colorado, Boulder.
After completing The Basic School and Field Artillery Officer’s Basic Course in 2006, he received orders to Battery A, 1st Battalion, 11th Marines. Lieutenant Colonel Diener served as Guns Platoon Commander for several months before deploying with the battery for a provisional security force mission in Camp Al Taqaddam, Iraq during Operation Iraqi Freedom from 2007 – 2008. After the deployment, he served as Fire Direction Officer and then deployed as the Battery Executive Officer with BLT 2nd Battalion, 4th Marines, 11th MEU between 2009 – 2010. He next served in the I MEF G-3 COPS section for a year before receiving orders to 1st Battalion, 10th Marines, where he served as the Assistant Fire Support Coordinator for 2nd Marines during Exercise BOLD ALLIGATOR and as Battery C commander.
Lieutenant Colonel Diener ended his active service in 2013 and joined 4th Tank Battalion in 2014 as the Fire Support Coordinator. He transferred to 5th Battalion, 14th Marines in early 2017 and commanded Battery N during Exercise AGILE SPIRIT in the Republic of Georgia in September 2017. He served as the Battalion Operations Officer in 2018 and Battalion Executive Officer in 2019 before transferring to 23d Marines. Lieutenant Colonel Diener served as the Assistant Operations Officer for 23d Marines and mobilized with the regiment in 2021 to support Operation ALLIES WELCOME, a multi-agency operation to relocate Afghan evacuees into communities across the United States. He then served in the 4th Marine Division G-3/5 as the Readiness Officer. Lieutenant Colonel Diener is currently assigned as the Commanding Officer, 5th Battalion, 14th Marine Regiment.
Lieutenant Colonel Diener is a graduate of the Marine Corps Expeditionary Warfare School, U.S. Army Field Artillery Captain's Career Course, and Marine Corps Command and Staff College. He earned a B.A. in History from the University of Colorado, Boulder; a M.A. in International Relations from University of Oklahoma; and a J.D. cum laude from California Western School of Law. His personal decorations include the Meritorious Service Medal, Navy and Marine Corps Commendation Medal (Gold Star in lieu of third award), and Navy and Marine Corps Achievement Medal (Gold Star in lieu of third award) . Lieutenant Colonel Diener is a Deputy District Attorney with a county District Attorney’s Office in CA.