Prosecutors agreed to not seek the death penalty when Katron Walker, 36, pleaded guilty in June to charges of murder and attempted murder for fatally stabbing his 4-year-old son, Collin, and trying to kill his 2-year-old son, Monte.
The 2006 attack happened just days after Walker's wife told him she wanted a divorce.
Vigo County Judge David Bolk mostly dismissed defense arguments about Walker's mental health.
A psychologist testified that Walker believed he needed to protect his sons' spirits because they would be "corrupt" if his marriage were to end.
Walker pleaded guilty June 22 to murder and attempted murder in the case. He had marijuana and methamphetamine in his system at the time of his arrest, police said.
August 24, 2009: Judge Weighs Sentence For Man Who Killed Son
June 22, 2009: Man Pleads Guilty To Abducting Sons, Killing 1
August 23, 2007: Man Charged With Killing Son Plans Insanity Defense
June 26, 2006: Police: Careful Consideration Goes Into Amber Alert
June 26, 2006: Walker Makes Court Appearance
June 20, 2006: Friends, Family Remember Slain Boy
June 19, 2006: Man Police Say Killed Son Could Face Death Sentence
June 16, 2006: Man Charged In Son's Slaying Makes First Court Appearance
June 15, 2006: Death Penalty Could Be Sought For Suspect In Boy's Death
June 14, 2006: Alert Delay? Police Say Threat To Boys Wasn't Immediately Clear
June 14, 2006: Police: Man Killed Son, Injured Another After Divorce Threat
June 14, 2006: Police: Boys, Father 'Accounted For' After Amber Alert
June 14, 2006: Amber Alert Issued For Two Boys