The Joplin Globe newspaper reports that 41-year-old Jeffrey Bruner was found guilty Thursday in the death of 37-year-old Derek Moore.
Police said the shooting happened after Bruner confronted his estranged wife as she left a local movie theater with the offensive line coach in November 2013.
The killing led to the cancellation of the school’s homecoming celebrations.
Moore was in his first year on the Missouri Southern football staff. He previously coached at Western Illinois University in Macomb, Illinois.
Sentencing is scheduled for May 18. The first-degree murder conviction carries a mandatory term of life without parole in Missouri.