A convicted mass-murder already facing three death sentences for crimes committed in Idaho has pleaded to the 1997 murder and torture of a 10-year-old California boy. The guilty plea brings Joseph Duncan his 10th life sentence, in addition to nine previous life terms and three death sentences, admitting to the death of four members of a family in north Idaho.  He also waived any appellate rights in 10-year-old Anthony Martinez murder and any motions filed in the California case. The Idaho case is still pending an appeal before the U.S. 9th Circuit Court. Duncan also pleaded guilty to six special circumstances, including the kidnapping, molestation and torture of Anthony before his death. In 2005 Duncan was charged for the murders of Brenda Groene, her fiancé Mark McKenzie and their oldest son Slade Groene in their Idaho home when they were bludgeoned to death with a hammer. Duncan will return to court April 5 to be sentenced for the boy's death.