LtCol Jernigan enlisted out of Colorado Springs, Colorado in May 1999 and attended basic training at MCRD San Diego and reported to the Basic Engineer Operators Course in Fort Leonard Wood, MO and upon completion received orders to 1st Transportation Support Battalion (TSB). While serving with 1st TSB, LtCol Jernigan attached to BSSG 1 for Exercise Native Fury 99-00 and again with MSSG-13 in support of OPERATION DETERMINED RESPONSE and what would become OPERATION ENDURING FREEDOM (OEF) in 2001-2002. After returning to 1st TSB, he deployed as part of CSSB-10 in support of OPERATION IRAQI FREEDOM from February to May 2003, returning early to attend MECEP preparatory school.

In September 2003, LtCol Jernigan attended the University of Colorado at Boulder. He graduated in 2007 with a Bachelor of Art’s degree in Geography and accepted his commission as a 2ndLt before attended The Basic School from June to Jan 2008. After TBS, LtCol Jernigan reported to Combat Engineer Instruction Company, Marine Corps Engineer School before reporting to 1st Combat Engineer Battalion in June 2008 where he was assigned to Mobility Assault Company as Platoon Commander for the Assault Breacher Platoon. In January 2009, he assumed the billet of Route Clearance Platoon Commander and deployed in support of 2d Marine Expeditionary Brigade– Afghanistan in April of that year. After redeployed in November of 2009, he assumed the duties of Sapper School OIC, responsible for training and evaluating combat engineer Marines and Officers, as well as the Assaultmen of the 1st and 5th Marine Regiments. In 2010 he was assigned to Company C, 1st Combat Engineer Battalion and deployed as the company Executive Officer in support of OEF 10.2 before executing orders to Marine Corps Engineer School in 2011.

From 2011 to 2013 LtCol Jernigan served in three billets. Route Clearance and Counter IED instructor, Officer Instructor and class advisor, and finally, Company Commander, Utilities Instruction Company. During this time, he successfully completed the Expeditionary Warfare Schools’ (EWS) distance learning program and was selected to attend the resident course in 2014.

Following his graduation from resident EWS LtCol Jernigan executed orders to 2d Combat Engineer Battalion where he served as the Company Commander for Mobility Assault Company as well as the Battalion Operations Officer before assuming duties at MARFOPAC as the G4 Engineer Plans Officer in 2018. In 2021 LtCol Jernigan began serving as the U.S. Forces Japan, Command Engineer, Chief of Construction. He is currently serving as the Executive Officer for Marine Aircraft Group - 12.

His personal awards include the Defense Meritorious Service Medal, Meritorious Service Medal (gold star in lieu of 2d Award), Navy and Marine Corps Commendation Medal w/ 2 gold stars and combat distinguishing devise, Navy and Marine Corps Achievement Medal, Combat Action Ribbon w/ gold star and second award Good Conduct Medal.