NASHVILLE (AP) — Tennessee is set to execute its first inmate since 2009, barring last-minute intervention from the U.S. Supreme Court or some unexpected change.

The lethal injection of 59-year-old Billy Ray Irick is scheduled for Thursday evening. Irick was convicted of the 1985 rape and murder of a 7-year-old Knoxville girl.

It would occur a week after Pope Francis revealed church teaching deeming the death penalty "inadmissible" under all circumstances.

A legal challenge against Tennessee's new three-drug cocktail continues on appeal. The state Supreme Court denied a stay Monday, saying the lawsuit wasn't likely to succeed. Gov. Bill Haslam said he won't intervene.

Attorneys have turned to the U.S. Supreme Court.

State and national mental health organizations filed a brief, saying the execution should be halted due to Irick's history of mental illness.