A convicted killer scheduled to be gassed to death in Louisiana Tuesday night had his last-minute appeal to save his life was turned down — paving the way for him to become the state’s first execution in 15 years.

The U.S. Supreme Court rejected a last-ditch effort to block Louisiana’s first execution using nitrogen gas, which is scheduled for Tuesday evening.

Louisiana plans to use nitrogen gas to execute death row inmate Jessie Hoffman next week. Here's what to know about the method and why its controversial.