Citing testimony from a state psychiatrist, Montana District Judge Richard Simonton indicated that the mental disabilities of Michael Keith Spell, 25, were mild enough that he could understand the case against him.
Spell is charged with the attempted kidnapping and murder of Sherry Arnold, 43. The Sidney High School math teacher was killed in January 2012 after going out for a morning jog. Her body was found more than two months later, buried in a shallow grave in a rural area of neighboring North Dakota.
Prosecutors have said they intend to seek the death penalty against Spell.
Co-defendant Lester Van Waters Jr., who was implicated by Spell as the killer, pleaded guilty in a deal with prosecutors that calls for him to testify against Spell.
Under that deal, Van Waters, 50, would escape a potential death sentence.
Experts for the defense said during a March competency hearing that Spell gets easily confused and is prone to forget even basic facts within minutes. They said that leaves him unable to meaningfully participate in the complex murder case, and noted that he was previously declared incompetent by a Colorado judge in a drug case.
But Simonton sided with the conclusions of Dr. Virginia Hill, a psychiatrist from the state mental hospital in Warm Springs who evaluated Spell when he was sent to the institution for testing last winter. Hill said Spell had matured mentally since the Colorado incompetency ruling, and he had benefited from being off drugs since his arrest in Arnold's murder.
"In Hill's opinion, Spell's adaptive functioning over the years has improved," Simonton wrote in his 16-page ruling. "The court agrees."
Lead defense attorney Al Avignone said Hill lacked the qualifications and expertise needed to fairly evaluate his client.
"We remain firmly convinced that Michael Spell is incompetent. Over 30 years I've had thousands of clients, and this is the first time I've had the opinion that my client is incompetent," Avignone said.
Avignone said he was considering filing a petition to the state Supreme Court to review the ruling, but he had not made a final decision.
The prosecution had cast Spell as a manipulative if mentally challenged conniver, eager to reduce his punishment by playing up his intellectual disability.
Spell's attorneys have not disputed he was involved in the events leading up to Arnold's murder, but they maintain that there is no conclusive evidence he was the one that killed her.
If Spell were ruled incompetent, the charges against him could be dismissed, and he would be committed to a state institution with the potential for eventual release.
Arnold's sister, Rhonda Whited-Rupp, said the prospect that Spell will stand trial "takes a load off" for her family.
"I know that will make my folks feel better, and me too," she said.
A trial date has not yet been set.
Still unresolved is whether Spell's disabilities — which both sides in the case describe as mild — will spare him the death penalty. A 2002 U.S. Supreme Court ruling banned the execution of mentally disabled defendants as cruel and unusual punishment.
Simonton said he was deferring a decision on that issue, but he addressed it indirectly in Friday's ruling.
"The court, with three justices dissenting, held that intellectually disabled criminals are not subject to the death penalty," Simonton wrote. "It did not say that intellectual disability equates to incompetency."
The case has unfolded against a backdrop of spiking crime rates in eastern Montana and neighboring parts of North Dakota, where an oil boom has transformed agricultural communities.
Court documents, including law-enforcement affidavits and testimony from Waters, said the defendants arrived in Montana in search of oil field jobs after a drug-fueled drive from Parachute, Colorado. Arnold died after Spell choked or otherwise asphyxiated her during an attempted abduction, according to prosecutors.
Following her disappearance, hundreds of Sidney residents turned out to search for Arnold, a popular teacher and mother of two who grew up on a ranch just outside town. The circumstances of her killing cast a pall over the once-quiet town now bustling with oil patch traffic.
Former Sidney Mayor Bret Smelser, a friend of Arnold's family, said a trial would help bring closure for the community.
"If this helps move the process along, the sooner the better for most of us out here," Smelser said. "It's taken a toll on the survivors because it's gone on so long and the outcome isn't predictable."