A botched execution by lethal injection in Oklahoma left an inmate writhing on the gurney for more than 40 minutes before he eventually died from a heart attack.

Oklahoma’s Department of Corrections said inmate Clayton Lockett was issued the first of the state’s new three-drug lethal injection combination on Tuesday. Thirteen minutes later the convicted rapist and murderer began breathing heavily and clenching his teeth, causing the doctor on scene to halt the execution.

Officials lowered the blinds to prevent those in the viewing gallery from watching what was happening in the death chamber. Officials said there was a “vein failure” during the execution.

Oklahoma Governor Mary Fallin has ordered a 14-day stay of execution for an inmate who was scheduled to die just two hours after Lockett.

Oklahoma had set up a new cocktail of chemicals after some drug makers imposed sales bans because they objected to the medications’ use in lethal injections.

  drugs, execution, failure, inmates, lethal injection, nation, news, oklahoma