BOISE, Idaho (AP) - California law enforcement officials are watching the sentencing hearing for convicted killer Joseph Duncan III closely in expectation of eventually trying him for at least one murder there.

The Riverside County, Calif., district attorney's office charged Duncan in January 2007 with the death of a Beaumont, Calif., boy.

In 1997, 10-year-old Anthony Martinez was forced into a car at knifepoint; his body was found 15 days later.

Duncan has also been linked to the 1996 slayings of two young half-sisters in Seattle.

The former Fargo man is eligible in Idaho for the death penalty after pleading guilty to kidnapping, torturing and killing Dylan Groene. His fate will be decided at hearings starting this week in Boise.

Duncan already has been convicted in Idaho state court of killing three people, including Dylan Groene's mother and brother, in a May 2005 attack near Coeur d'Alene.