Eugene Butler was known to be a bit of a nutcase. In fact he spent the last seven years of his life in an asylum.
He had lived almost all of his life outside of Niagara, North Dakota. He was known as being a recluse, and was also very paranoid. He spent quite a bit of his time avoiding people, with the only one's he spoke to being young men he hired as farm hands.
When Butler died in the local nuthouse no one really suspected him of anything except of being a bit weird, but two years after his death a little surprise was to be had by all.
During a routine excavation of the late Butler's house a hidden trapdoor was found to open to the ground beneath the floor. Upon a small amount of digging a couple of bones were found, then a skull. The local cops were called.
Over the next few days six complete skeletons were uncovered from the ground beneath Butler's floorboards. The coroner said they had all been males, between the ages of 15-18. As no one knew of anyone that age who had gone missing the bodies went unidentified. They remain so.
All had been killed by crushing blows to the backs of the head. As there were no living witnesses, and Butler himself was dead, it was theorized that he had thought the farm hands were planning to rob him, so he decided to strike first. Those who had contact with Butler had heard him talk about such fantasies before, so it was decided that was the motive.
It would seem though that Butler may have been an early 1900's Gacy, Nilsen or Corll, but as the local law enforcement knew little of sex crimes they didn't think about this as a more logical motive.
Credit murderpedia/ The Wacky World of Murder