Actually Boone Helm (whose given name was Levi Boone Helm) was born in Kentucky and his family actually moved to Monroe County, MISSOURI when he was just a young child. Boone Helm's family never lived in IOWA! Sorry to disappoint you.
He actually shot and killed a man in Monroe County, MO, fled the county but was hunted down, tried for murder to which the plea was "not guilty by reason of insanity". He later fled Missouri and headed west where he terrorized the folks out there and in Canada.