An Oklahoma man claims that his stepfather "jumped him" after a long night of drinking; the fight began when Denver Lee St. Clair allegedly made disparaging remarks about 33-year-old Brad Davis' mother.

The tiff intensified after St. Clair, according to Davis, attempted to punch him the face.

The Daily Mail reports that the father and son brawled before Davis allegedly pulled the elastic band of his victim's underwear over his head from behind, killing him.

Davis said he acted in 'self-defense'. However the man's death has been ruled a homicide, with the State Medical Examiner's office finding St. Clair died of suffocation and blunt force trauma to the head.

Police believe Davis altered the crime scene to make it look like the men had had a fight before he called 911.

"We continued our investigation and uncovered evidence that led us to believe that this was more than just a fight," Sheriff Mike Booth said.

Davis was booked into the Pottawatomie County Jail and faces murder charges.