Police said they had a suspect in custody, Jeffery L. Bruner, 39, who was being held on a murder charge without bond, The Joplin Globe reported.
Police said Moore, 37, was shot in the parking lot of the Northstar 14 Theatres at 9:50 p.m. Friday, the newspaper said. No motive for the shooting was reported.
Missouri Southern canceled its homecoming activities, including its home football game against Lindenwood, in response to the assistant coach's death.
Moore, the father of a 7-year-old boy, had joined the Lions staff as offensive line coach this year. He previously coached three seasons at Western Illinois University and had a total of 14 years experience in the collegiate coaching ranks.
"We are stunned and deeply saddened by this tragic incident, and our prayers are with Derek's family," MSSU interim President Alan Marble said in a release. "We are ensuring that our employees and students have the emotional support they need during this difficult time."
Head Coach Daryl Daye called Moore's death "an unspeakable loss" for the campus sports community.
"Derek was new to Missouri Southern, but he was embraced by our campus and community," Daye said. "He was a very likable person who always had a smile on his face and made friends easily with our staff and players."
Athletics Director Jared Bruggeman said the slaying "deeply saddened" the Missouri Southern athletics community.
"In times like this, our priority is to make sure we are there for our student-athletes, coaches and support staff in whatever way necessary," he said.