Alfred enters his sixth year as the Head Athletic Trainer at Southeast Missouri State University. Previously, Alfred worked at the University of Missouri where he served as an assistant athletic trainer for five years. At Mizzou, Al worked with track and field, baseball, and spent two years as the top assistant for the football team.

Before working at the University of Missouri, Castillo spent two years as an assistant athletic trainer at Texas A&M University. At Texas A&M, he was in charge of the track and field teams and assisted with football. Prior to that, he was the head athletic trainer for the P.S.J.A. School District in South Texas for three years. He also spent 15 months working as a rehab coordinator at a physical therapy clinic before switching to the high school setting.

Castillo is a member of the National Athletic Trainers Association, the Missouri Athletic Trainers Association, the Southwest Athletic Trainers Association and the USAPL.

Castillo received his bachelor's degree from the University of Texas-Pan American, and earned his master's in Sports Physiology from Texas A&M. He and his wife, Mary Ann, have a son Matthew (16) and a daughter, Jordyn (11).