BOISE, Idaho-The 9th U.S. Circuit Court of Appeals has thrown out the death penalty of Joseph Edward Duncan III, saying he should have been given a competency hearing before he was allowed to waive his appeal.

The appellate court handed down the ruling Monday, ordering U.S. District Court Judge Edward Lodge to hold a retrospective competency hearing for Duncan.

Duncan was sentenced to die in 2008 for kidnapping, torturing and murdering a 9-year-old Coeur d'Alene boy in 2005. Prosecutors said Duncan snatched Dylan Groene and his 8-year-old sister from their northern Idaho home after killing their older brother, mother and mother's fiance. Duncan kept the children at a remote Montana campsite for weeks before killing Dylan and returning with Dylan's sister to Coeur d'Alene, where he was arrested.