In 1978 an undercover cop was killed by the sheriff in Rock Springs.
The oil boom of the 70s brought seedy characters to Rock Springs.
Mike Rosa was undercover investigating them. Rosa's wife later testified that he had proof of corruption in the city government.
On July 15, Sheriff Ed Cantrell met Rosa outside a bar. Cantrell shot and killed Rosa in the parking lot. The reason for the shooting remains disputed.
Cantrell's lawyer argued that he shot Rosa in self-defense. Cantrell was acquitted and let go. Critics of the decision argued that Rosa was killed because he had incriminating information on Cantrell.
People Magazine called Rosa "a good cop in a bad town."
Explore the evidence in the Edward Cantrell murder trial and investigation records at UW's American Heritage Center.