BOISE, Idaho - Six life prison terms were added Monday to the death sentences of Joseph Edward Duncan III, with a judge telling the confessed child-killer that his horrific rampage of murdering four family members and abducting and sexually torturing a young brother and sister "exceeds the bounds of human understanding."

In August, a federal jury handed Duncan three binding death penalty sentences for the kidnapping, torture and murder of 9-year-old Dylan Groene, who was snatched from his Coeur d'Alene home on May 16, 2005, with his sister Shasta and held for weeks at remote campsites in western Montana.

Duncan kidnapped the children after barging into their northern Idaho home and using a hammer to kill their 13-year-old brother, Slade Groene, their mother, Brenda Groene, and her fiance, Mark McKenzie.

In a state court hearing Monday, Duncan was sentenced to three life terms for those murders. He had previously been sentenced in state court in 2006 to three life terms on kidnapping charges for binding all three victims before they were bludgeoned.

Shortly after the state hearing, U.S. District Judge Edward Lodge sentenced Duncan to three additional life terms, one for kidnapping Shasta Groene, the lone survivor of the Duncan's violence, and one each for sexually abusing Shasta and her brother.

"By any stretch of the imagination, your rampage … exceeded the bounds of human understanding," Lodge told Duncan. "These crimes … were unfathomable, cruel and sadistic."

Duncan, 45, was handcuffed and whisked away by U.S. marshals. Prosecutors say the Federal Bureau of Prisons will determine where he should be held, a decision that may be influenced by whether California authorities pursue criminal charges against Duncan for the 1997 abduction and murder of a 10-year-old boy from Riverside County.

Duncan, a convicted pedophile originally from Tacoma, Wash., who acted as his own attorney during the death penalty phase last summer, has said his violence was motivated by a need to seek revenge on society.

Offered a final chance Monday to explain his actions or offer remorse to Groene relatives, Duncan was unapologetic and instead quoted a biblical passage he attributed to St. Paul.

"I care very little why I'm judged by your or by any human court. Indeed, I do not even judge myself," Duncan said. "My conscience is clear, but that does not make me innocent. The truth is my only judge."

Duncan pleaded guilty last December to 10 federal counts stemming from his kidnapping and sexual abuse of Dylan and Shasta, who was 8 at the time, and the slaying of Dylan. Three of those charges qualified for the death penalty.

During his federal death penalty hearing, prosecutors spelled out the grim details of the more than five weeks the children spent as Duncan's captives.

Prosecutors said that at campsites in Montana's Lolo National Forest, Duncan raped, tortured and threatened the children before shooting Dylan in the head on June 22, burning his body and ordering Shasta to help bury the remains. Jurors also watched a horrifying video Duncan made of his sexually abusing, torturing and hanging Dylan until the boy lost consciousness.

After Dylan's death, Duncan took Shasta back to Coeur d'Alene, where the girl was rescued July 2 after a waitress recognized her while the two were at a restaurant, ending a nationwide manhunt.

The jury deliberated for three hours before imposing three separate death sentences. Four of those jurors, along with Steven Groene, the father of Shasta, Dylan and Slade, attended Monday's sentencing hearing.

Prosecutors have said the law requires the multiple death sentences and life terms, and would act as safeguards if convictions or sentences are overturned on appeal.

Two of the federal life sentences will be served concurrently, with the third served consecutively.

The three life terms handed down in state court Monday will be served concurrently, but consecutive to the three consecutive life terms imposed in 2006.

Lodge also ordered Duncan to pay $100,000 in restitution to cover future costs of counseling and treatment for Shasta. Lodge acknowledged it's unlikely Duncan will be able to pay that cost, but he imposed the fine should Duncan be able to profit in any way from selling the rights to his story.

Duncan has 10 days to file a notice of intent to appeal his federal sentence.