Alabama Corrections Commissioner John Hamm said the state halted the scheduled execution of Alan Miller after they determined they could not get the lethal injection underway before a midnight deadline.

“Due to time constraints resulting from the lateness of the court proceedings, the execution was called off once it was determined the condemned inmate’s veins could not be accessed in accordance with our protocol before the expiration of the death warrant,” Hamm said.

A psychiatrist hired by the defense found Miller suffered from severe mental illness and delusions but also said Miller’s condition wasn’t bad enough to use as a basis for an insanity defense under state law.

Miller’s attorneys said the state lost the paperwork requesting his execution be carried out using nitrogen hypoxia, a method legally available to him but never before used in the U.S.

When Alabama approved nitrogen hypoxia as an execution method in 2018, state law gave inmates a brief window to designate it as their execution method.

Miller testified that he turned in paperwork four years ago selecting nitrogen hypoxia as his execution method, putting the documents in a slot in his cell door at the Holman Correctional Facility for a prison worker to collect.

issued a preliminary injunction on Tuesday blocking the state from killing Miller by any means other than nitrogen hypoxia after finding it was “substantially likely” that Miller “submitted a timely election form even though the State says that it does not have any physical record of a form.”.

Nitrogen hypoxia is a proposed execution method in which death would be caused by forcing the inmate to breathe only nitrogen, depriving him or her of the oxygen needed to maintain bodily functions.