Mr. Allgier, whose face is a green mask of neo-Nazi tattoos, charted a bloody path to reach this point.

Image Curtis Allgier, a white supremacist convicted of murdering a prison officer. Mr. Corbett calls Mr Allgier's behavior "exceptionally rare.” Credit... Francisco Kjolseth/The Salt Lake Tribune, via Associated Press

He had been serving a state prison sentence for burglary and forgery in June 2007 when he complained of back pain and was taken for an examination at the University of Utah. After being unshackled for a magnetic resonance imaging scan, he grabbed a gun from Stephen Anderson, the corrections officer who had been escorting him, fatally shot Officer Anderson and escaped from the hospital. He stole a car and led the police on a chase before being caught later that day at an Arby’s restaurant.

Officer Anderson, 60, was described in memorial commendations as a “quiet and gentle” corrections officer who was well liked and respected by inmates and colleagues, and had stayed on the job even after becoming eligible to retire. He had raised horses, and one of his children described him as irreplaceable on the day that his killer was sentenced.

To avoid the death penalty, Mr. Allgier pleaded guilty to murder in 2012 and was sentenced to life in prison without any possibility of parole. He is trying to withdraw that plea.

The ruling from the Utah Supreme Court describes how Mr. Allgier burned through lawyers as his case worked its way through the legal system. The Salt Lake Legal Defender Association made multiple requests to withdraw from representing him. After that, he “apparently became dissatisfied with his new counsel,” the court said, and asked to represent himself.

A new lawyer was appointed to represent him during appeals, and less than a month later, that lawyer asked to withdraw, citing an “irreparable breakdown” in their relationship. Mr. Allgier had suggested that “it would get very ugly” if the lawyer did not withdraw.