"Simon told police that he was walking his dog with his girlfriend in the 3000 block of North Fox Street when he told the dog to poop."

"He then heard a voice from a ground-level apartment yelling at them and asking if they were going to train the dog or just yell at it, according to the probable cause statement. Simon said he tried to ignore the yelling but then saw the man point a gun at him."

From "Suspect in homicide near Coors Field opened fire because of dispute over dog poop, police say/Michael Close, 36, accused of firing on victims from his apartment while they were walking their dog" (Denver Post).