KALISPELL, Mont. -

David Day appeared in Flathead County District Court Thursday morning and pleaded not guilty to negligent homicide after a fight left another man dead on June 1.

Court documents reveal that prosecutors are hinging their case on an all-day drinking binge that ended in an argument with Gerald Payne, a neighbor at the Montana Village in Evergreen. The pair were fighting when Day allegedly hit Payne in the face. Payne fell down a flight of stairs and died as a result of his injuries.

If convicted, Day could face up to 20 years in prison.