While some states have explored new methods, others have reauthorised some of the earliest ways US officials used to put people to death.
As of this year, nine states have approved execution by electric chair, with South Carolina using it as their default method.
Electrocution “has a horrible history of botched executions”, Maher said, and errors with these executions is one of the reasons why states introduced lethal injections in the first place.
In 1997, Pedro Medina’s head caught fire as he was put to death in an electric chair in Florida.
“A solid flame covered his whole head, from one side to the other. I had the impression of somebody being burned alive,” his attorney Mike Minerva said, according to the Los Angeles Times.
A method once used as punishment in the military and in times of war, firing squad executions have also proven susceptible to human error.
Mikahl Mahdi was executed by a three-person firing squad last year after admitting to killing an off-duty police officer in 2004. But his lawyers say his death was prolonged because the bullets missed his heart and instead hit his liver and other organs.
In July, Idaho became the first state to use a firing squad as its primary method of execution after it ran into issues with lethal injections. Mississippi, Oklahoma, Utah and South Carolina also authorise this execution method.
Alonzo Lunsford, a former US Army sergeant who survived being shot seven times by Hasan in the Fort Hood attack, told the BBC the firing squad was a “befitting” method to end his life because lethal injection and a gas chamber would be “doing him a favour”.
Hanging was the main method of execution in the US until the 1890s, and several Asian countries including Japan and Singapore still use this method. But in the US, no states authorise hanging because of its “terrible” history, Maher said.
“Hanging has such a terrible association with racial violence and lynching in the states,” she said. “So that is why there’s no state that’s using hanging or has authorised that method to be used.”
