The 9th U.S. Circuit Court of Appeals has ordered that a competency hearing be conducted for convicted kidnapper, torturer and murderer Joseph E. Duncan III.

The appeals court said in an opinion Monday that Duncan should have received a competency hearing before he was allowed to waive an appeal of a death sentence.

No date has been set for the hearing before U.S. District Court Judge Edward Lodge. It likely will be in Boise.

Duncan was sentenced to die for kidnapping, torturing and murdering a Coeur d'Alene boy, 9-year-old Dylan Groene, in 2005.

Duncan was sentenced to death following a capital sentencing hearing in 2008, at which he represented himself.

His stand-by legal counsel during that sentencing hearing filed a notice of appeal, which was done against Duncan's wishes at the time.

"The district court did not, however, hear testimony or take evidence on whether Duncan was competent to waive his right to appeal," U.S. Attorney Wendy Olson, in Boise, said Monday.

"The Ninth Circuit has now instructed (Lodge) to do so."

If the U.S. District Court again finds that Duncan competently waived his right to appeal the sentence, then the court should reinstate its previous order, the appeals court ordered.

If the lower federal court finds Duncan didn't competently waive his right, then it needs to look at whether he competently decided to have no attorney during the penalty phase hearing.

"If the court further finds that (Duncan) did not competently waive his right to counsel, then it should vacate (his) sentence and convene a new penalty phase hearing with (Duncan) properly represented," the court wrote in its opinion.

The appellate judges noted that although he frequently appeared rational in court, Duncan had unusual religious beliefs that played a significant role in how he conducted his defense.

And while two experts appointed by the lower federal court found that Duncan was competent to stand trial, the appellate court noted that some experts contacted by the standby attorneys found that Duncan was delusional and psychotic.

During the sentencing hearing, Lodge did make an effort to determine if Duncan was competent. He ordered Duncan to be examined by a local psychologist, who said that while Duncan's thoughts were "somewhat unusual," Duncan wasn't delusional and that he'd waived his right to an attorney knowingly and voluntarily. Lodge went on to have Duncan evaluated again, this time by the Federal Bureau of Prisons. For that evaluation, a forensic psychologist watched Duncan over a period of six weeks, reviewed his mental and medical health records and spoke to his attorneys. Duncan refused to participate in the evaluations.

The forensic psychologist found no evidence that Duncan was psychotic, and said while he held some strong religious views she didn't think they were delusional.

Three experts contacted by the standby attorneys found that Duncan suffered from "delusional beliefs, paranoia, grandiosity, and psychotic breaks with reality," according to the court ruling.

Those experts said Duncan's mental defects rendered him incapable of rationally understanding the court proceedings. The appellate court said Lodge could have also considered letters written by Duncan from jail, some of which posed rational arguments and philosophical observations, and others that were deemed "unusual," including statements about his beliefs and how they played a role in how he conducted his defense.

Olson said that since July 2005 Duncan has been found competent by every court or jury to consider the issue.

Olson's spokeswoman, Pamela Bearg, said experts will probably be called to testify during the upcoming competency hearing. She said Olson's office didn't know who would testify.

Duncan's appellate federal defender, Joseph Schlesinger, in Sacramento, declined to comment.

After Duncan was sentenced to death in U.S. District Court in Idaho, he was transferred to Riverside County, California, to face state charges in connection with the 1997 murder of a 10-year-old boy.

Both a jury and the presiding judge found that Duncan was competent to proceed in that case.

Prosecutors said Duncan snatched Dylan Groene and his younger sister from their home at Wolf Lodge after killing three of their family members in 2005. Duncan kept the children at a remote campsite in Montana for weeks before killing Dylan and returning with Dylan's sister, 8-year-old Shasta, to Coeur d'Alene, where he was arrested.

- The Associated Press contributed to this report