A fatal shooting on a Tuesday night in Alamosa, Colorado, ended the life of 58-year-old John Cossel of Monte Vista. Officers responded to reports of possible gunshots in the 200 block of State Avenue and found Cossel with a single gunshot wound.

A 57-year-old Alamosa resident, Kawanna Nelson, was at the scene and cooperated with investigators. Arrest documents describe Nelson and Cossel as good friends who had argued earlier when Cossel wanted his car keys and Nelson said she worried he was unfit to drive. The papers say Cossel left, returned, and began banging on Nelson’s door. Nelson told investigators she opened the door armed with a 9mm Smith and Wesson after calling who was there twice, and that Cossel entered and went at her before she fired one shot.

Nelson was taken into custody and charged with second-degree homicide in Cossel’s death. What details about the moments before the shot might clarify whether this was self-defense or something else?