Prosecutors plan to seek a retrial for a man whose conviction for killing nine people at a Buddhist temple was overturned after the U.S. Supreme Court refused to reverse a decision that threw out his confession.

Jerry Cobb, a spokesman for the Maricopa County Attorney's Office, said Tuesday that prosecutors will file charges in the coming days against Jonathan Doody in the 1991 killings at the Wat Promkunaram temple west of Phoenix. Cobb said it will take some time to prepare the charges.

"This is a 20-year-old case," Cobb said. "We have to get our arms around it."

The Supreme Court on Tuesday refused to hear an appeal by Arizona officials who asked for a re-examination of a lower court's decision to throw out Doody's confession.

Doody was convicted of the slayings of six priests, a nun and two helpers during a robbery at the temple. The bodies were found arranged in a circle, and all had been shot in the head.

Doody, who was 17 at the time of the killings, was sentenced to 281 years in prison after he was convicted of murder, armed robbery and other charges in the slayings. He maintained that he's innocent.

The 9th U.S. Circuit Court of Appeals found Doody's Miranda warnings were inadequate and threw out the conviction, ruling the confession was involuntary, partly because he wasn't properly read his rights by the officers interrogating him.

Lawyers for the state contended that Doody's confession was reliable and admissible and cited an Arizona court's decision that upheld the confession.

Arizona Attorney General Tom Horne, whose office defended the conviction in appeals courts but won't handle a possible retrial, said there's other evidence of Doody's guilt even without the confession.

Horne said he expects that Doody would remain behind bars while he awaits a retrial.

Victoria Eiger, a lawyer who handled Doody's appeals, said there's no substance left to the case after Doody's confession is taken out of the picture. "It was the cornerstone of the state's case," Eiger said.

Four Tucson men were arrested in the killings, but were released after investigators found they weren't involved.

Doody and another teen were arrested after investigators linked them to the murder weapon.

Co-defendant Alessandro Garcia, who pleaded guilty in the case to escape the death penalty in exchange for his testimony, said Doody was the triggerman. Doody was spared the death penalty because the judge couldn't determine whether he fired the weapon.

Garcia testified that the two wanted to steal large amounts of gold and cash that they believed to be kept by the monks. Investigators said the robbery netted some cash and electronics gear.

The killings stirred outrage in Thailand, where monks are revered and where most men serve a brief stint as apprentice monks at some point in their lives.

Doody was born in Thailand to Buddhist parents. His mother belonged to the temple.