Arizona is changing the mixture of drugs it uses for lethal injections after an execution this summer left an inmate alive for almost two hours, the Associated Press reports. In a letter to Governor Jan Brewer, Department of Corrections Director Charles Ryan said that the state would be abandoning its current sedative and painkiller combination, potentially replacing it with an older alternative. The news comes in response to an independent report investigating the death of Joseph Rudolph Wood, a convicted murderer who was executed by lethal injection earlier this year. The process, which should have taken minutes to work, dragged on as Wood "gasped and snorted," eventually taking an hour and 57 minutes before he was pronounced dead. It's the latest incident to raise questions about whether lethal injection, adopted as a supposedly more humane alternative to older execution methods, can actually deliver a painless death.

Wood's death is one of several failed or prolonged lethal injections. Earlier in 2014, Oklahoma inmate Clayton Lockett suddenly regained consciousness during his execution; it was stopped, but Lockett died soon after of a heart attack. The problem reportedly stemmed from a misplaced needle, and the White House condemned Lockett's death as inhumane. Oklahoma and Arizona, along with other states, have temporarily halted executions as they investigate the deaths.