Staley's attorneys want a hearing to decide whether he's mentally competent to be executed. Staley's case long has focused on whether his competency can be achieved only through the mandated use of drugs.
Staley was convicted of the October 1989 fatal shooting of Bob Read, the manager of a Steak and Ale restaurant, during a botched robbery.
Authorities tied him and two companions to a series of robberies, assaults and at least one other murder during a spree across Colorado, Kansas and Oklahoma.
More: Steven Kenneth Staley Death Row Info