ST. LOUIS (AP) — The anesthetic that caused the overdose death of pop star Michael Jackson is now the drug for executions in Missouri. That's causing a stir among critics who say the state can't guarantee a drug untested for lethal injection won't cause pain and suffering for the condemned.

The Missouri Department of Corrections is switching from its longstanding three-drug method to a single drug, propofol, which has never been used in an execution in the U.S.

Until recently, the 33 states with the death penalty used a virtually identical process: Sodium thiopental was administered to put the inmate to sleep, and then two other drugs stopped the heart and lungs. After the makers of sodium thiopental stopped selling it for use in executions, supplies ran out and states began seeking alternatives.