Convicted killer Joseph Edward Duncan III.

BOISE -- A federal judge in Boise has declared convicted child killer Joseph Edward Duncan III mentally competent

The ruling handed down Thursday means the sentencing phase of Duncan's murder and kidnapping case can proceed.

Duncan faces the death penalty on three of 10 federal charges related to the 2005 kidnapping of young Dylan and Shasta Groene and the slaying of Dylan. The two were snatched from the Coeur d'Alene home then taken to the wilderness in western Montana where they were tortured and abused.

A hearing on whether Duncan should be allowed to serve as his own attorney during the sentencing phase is scheduled Monday in Boise.

Earlier this year, Duncan asked U.S. District Judge Edward Lodge to allow him to represent himself, claiming his attorneys could not ethically represent his ideologies.

After that request, Lodge suspended the hearing and ordered Duncan to undergo psychiatric evaluations to determine his mental fitness.