The Mississippi Supreme Court will allow a psychiatric evaluation for Gerald James Holland, who is scheduled to be executed May 20.
Holland's attorney Louwlynn Vanzetta Williams sought the evaluation in an attempt to halt the execution.
Assistant Attorney General Marvin White had argued that Holland never showed a substantial need for a neurologist.
In Thursday's order, Supreme Court Justice James Kitchens said Dr. Mark Webb could conduct the evaluation in support of Holland's clemency petition.
Holland, of Adams County, was sentenced to death for raping, beating, stabbing and suffocating 15-year-old Krystal King in 1987. Now 72, Holland is the oldest death-row inmate in Mississippi.