BOISE, Idaho - Joseph Duncan III, the man accused of killing three members of a northern Idaho family so he could molest two children, has been sued by a relative of the victims.

Steven Groene filed the wrongful death lawsuit Wednesday in U.S. District Court, alleging that Duncan, a convicted child molester who had been living in Fargo, N.D., was responsible for the deaths of 13-year-old Slade Groene, 9-year-old Dylan Groene and their mother, Brenda Groene.

Steven Groene also claims that Duncan caused intentional infliction of emotional distress and battery against Shasta Groene, who was 8 at the time of the May 2005 slayings and abductions.

Steven Groene is the father of Slade, Dylan and Shasta and the ex-husband of Brenda Groene.

In the lawsuit, Groene asks a judge to prevent Duncan from profiting from the crimes by writing books, providing television or movie content or any other activities. He also asks for a jury trial and monetary damages in an amount to be proven in court.

Duncan, 43, a Tacoma, Wash., native, faces the death penalty if he is convicted in an Idaho court on three counts of murder. He is accused of using a hammer to kill Brenda Groene; her fiance, Mark McKenzie; and Slade Groene, at the family's home east of Coeur d'Alene.

Prosecutors allege he killed the three so he could abduct and molest Shasta and Dylan Groene.

Duncan was arrested July 2, 2005, at a Denny's restaurant in Coeur d'Alene while eating with Shasta. Dylan's remains were later found at a remote campsite near St. Regis, Mont.

On Tuesday, a spokeswoman for federal prosecutors said they, too, plan to seek the death penalty once they charge Duncan in the abduction of the two children. Jean McNeil, spokeswoman for U.S. Attorney Tom Moss in Boise, declined to say exactly what federal charges Duncan would face.

Steven Groene claims that both he and his daughter, now 9, have suffered severe emotional distress, medical expenses and the loss of the care and companionship of family members as a result of Duncan's actions.