The Arizona Supreme Court on Tuesday threw out the death sentences of a Tucson man who bludgeoned his girlfriend and her two children to death in 1984 after lying in wait for each of them, ruling that the murders weren't especially heinous even though they were "atrocious" and "senseless."

The state's highest court unanimously vacated two death sentences for James Granvil Wallace, 61, and imposed two sentences of life in prison for the children's killings. That's on top of the life sentence he's already serving for killing his girlfriend, Susan Insalaco.

While the justices wrote that the Feb. 1, 1984, murders of Insalaco, her 12-year-old son, Gabriel, and her 16-year-old daughter, Anna, in their Tucson apartment were heinous in layman's terms, they weren't according to the letter of the law.

That's because the justices found that Wallace didn't knowingly inflict more wounds on the family than he thought were necessary to kill them.

Wallace was living with Insalaco and the children when he came home drunk Jan. 31, 1984, and she told him that he needed to move out, according to court records.

The next day, Insalaco went to work and the kids went to school. Wallace attacked each of them when they arrived home separately after hiding behind the front door.

When Anna came home, court records say that Wallace attacked her from behind and slammed a baseball bat into her head at least 10 times, so hard that the bat broke. Even so, Anna lay moaning and still alive, so Wallace told police that he dragged her into the bathroom and rammed the broken bat into her neck, down her chest cavity and out her back.