Butler farmed near Niagara, in North Dakota, and was known locally as odd. In 1906 he was declared insane and sent to the state asylum at Jamestown, on the strength of his behaviour and not of any offence. He died there.
In 1913 workmen at the farmhouse found six male skeletons buried beneath the building. They had been killed by crushing blows to the back of the head. They were identified, so far as they were identified at all, as farmhands and drifters who had worked for him between about 1900 and 1906.
There was never any prosecution. He was in an institution before the bodies were found and dead before anyone connected them to him, so no charge was laid, no evidence was tested and no court ever considered the case.
The entry is therefore an account of six unexplained deaths under one man's house rather than a record of convictions, and it is marked as one in which nobody was convicted.
The selection is the same as in several entries here: he hired men whose absence nobody would report. The difference is that this case was never even alleged against him while he was alive to answer it.