Accused: Did I Do It? S01E01 - Pocketknife Killer or Vulnerable Vacationer?

A day out on the river with friends ends in a deadly encounter, when a man stabs five people with a pocket knife, following a terrifying confrontation.  The Defense argues the man believed his life was in danger and he acted in self-defense.  With the entire incident recorded on cellphone, the Prosecution believes the man was the aggressor and this was intentional homicide. Is he a pocket knife killer or a vulnerable vacationer?