The U.S. Supreme Court denied the Georgia attorney general’s request to lift a stay of execution a federal appeals court issued less than an hour before Warren Hill was to have been executed Tuesday evening for a 1990 murder.

The justices in Washington offered no reason, simply writing Thursday that the application to vacate the stay was denied.

A panel of the 11th U.S. Circuit Court of Appeals voted 2-1 Tuesday to stop Hill’s execution to consider his appeal based on “new evidence” that the experts who testified in 2000 that he was not mentally retarded and was eligible for the death penalty had now changed their opinions. A psychiatrist and two psychologists who worked for the state recently told Hill’s lawyer that they had been rushed to make an evaluation 13 years ago, that they are now more experienced than they were then and there had been advances made in the profession’s understanding of mental retardation.

Hill was been sentenced to die for beating to death his cellmate at a prison where Hill was already serving a life sentence for murdering his 18-year-old girlfriend in 1986.