Trooper Crumley apparently had been working radar and had contacted a violator.
Trooper Crumley was killed by two shots from his service revolver. A driver's license was found beside his body.

It was later determined that two brothers had brutally murdered a man and had been
stopped by Trooper Crumley shortly afterwards. While Trooper Crumley had the driver
spread-eagled on the hood, apparently to search him for weapons, the passenger
pulled a gun and the pair then shot the Trooper. They then kidnapped a woman and
forced her to drive them around for several hours near Lake Murray. One of the men
the shot himself and the other one forced the woman to drive him to a third brother's residence after leaving the fatally injured man at a hospital.

Troopers and other officers arrested the man after the woman reported the incidents.
The twenty-two year-old man was convicted and sentenced to life imprisonment.

Also see: http://www.brightok.net/chickasaw/ardmore/county/crumley.html