Simon Peter Nelson murdered his children in 1978 with a rubber mallet and a knife after a family friend told him that his wife intended to divorce him. The children ranged in age from three to 12.
The Illinois Prisoner Review Board voted unanimously Thursday to deny Nelson's recent parole request. It's the 13th time he's been turned down since he became eligible in 1986.
Nelson is serving 100 to 200 years at the Graham Correctional Center in Hillsboro, south of Springfield.
More than 60 people wrote letters to the Prisoner Review Board opposing his parole, while a handful supported his release.