An FBI special agent participates in a post-blast crime

An FBI special agent participates in a post-blast crime scene investigation during Guardian Shield at Marine Corps Air Station Miramar, California, Aug. 28, 2018. Guardian Shield 2018 is a U.S. Army Reserve Criminal Investigation Command (CID)-led training exercise held in Coronado, California, that certifies Army Reserve special agents on courses they need to progress in their career, as well as provides training to active duty Army CID, Naval Criminal Investigative Service (NCIS) agents, Marine Corps CID, civilian law enforcement and Navy and Marine EOD. In its ninth year, Guardian Shield continues to be one of the most in-depth training events for military special agents, where they can perfect their skillset, learn the latest cutting-edge training and foster relationships with other branches for seamless cohesion in joint operations and on the battlefield. (U.S. Army Reserve photo by Sgt. Audrey Hayes)