Trooper Harper was shot and killed after stopping a white supremacist.

Trooper Harper was on patrol on US 60, two miles east of Springfield when he was passed by a speeding pickup. The pickup pulled off onto a farm road and waited for Trooper Harper. As Trooper Harper pulled up the man exited his vehicle and opened fire with an automatic weapon, killing Trooper Harper before he could exit his cruiser. The suspect, Glennon Paul Sweet, was executed on April 4, 1998, for the murder of Trooper Harper.

Trooper Harper had been with the agency for 18 years. He was survived by his wife, three sons and a stepdaughter. Interred: Rivermonte Memorial Gardens.