A death row inmate set to be executed by firing squad Friday is scrambling to block his execution after losing an appeal at the Utah Supreme Court and failing to persuade the state parole board to grant him clemency.

Ronnie Lee Gardner's attorneys are now ramping up a federal civil rights lawsuit filed last week against the Utah Board of Pardons and Parole. Gardner contends the commutation hearing process is tainted because lawyers that represent the board and the state prison all work for the Utah attorney general's office — the same entity that sought Gardner's death warrant and argued against a commuted sentence.

The case is assigned to U.S. District Judge Tena Campbell, but no hearing had been set Tuesday.

The parole board on Monday rejected Gardner's efforts to get his death sentence reduced to life in prison without parole, and hours later, the Utah Supreme Court unanimously denied Gardner's appeal.

In its 57-page ruling, justices said it was too late for Gardner to challenge his sentence and that he had been treated fairly throughout his 25 years of appeals.