Brad Davis, 33, has been accused of suffocating his stepdad by pulling his underpants and stretching them up over his head and around his neck.
County Sheriff Mike Booth said: “I’d never seen this before, but when we looked at our victim the waistband of his underwear was around his neck.”
According to statements, the pair began fighting at the home of Denver St Clair, 58, when he insulted his wife Tressia, who is Davis's mum.
Davis, a former US Marine, apparently told police that he punched his stepdad unconscious after the older man "jumped him", before giving him an "atomic wedgie".
Apparently the elastic of the underwear was pulled so tightly that it left ligature marks around St Clair's throat.
However, while Davis insisted that he acted in self-defence after a brawl, he has been charged with murder.
“I’d never seen this before, but when we looked at our victim the waistband of his underwear was around his neck”
Sheriff Booth said: “We continued our investigation and uncovered evidence that led us to believe that this was more than just a fight.”
Court documents show that Tressia said her husband thought Davis owed him £4,000 in rent. His stepson had apparently been living in his trailer house and, on 20th December, it was claimed that St Clair had sai he was going to "pull Brad out of that trailer by his throat."
It has also emerged that a restraining order was placed on Mr St Clair in 2008 after a complaint from his wife. She claimed he had grabbed her by the neck and hurled her through a bathroom door.
The couple had filed for divorce four months ago - the third time they had begun divorce proceedings during their tumultuous marriage.
Davis has been detained in Pottawatomie County Jail without bail.