The pax conveniently remembers nothing.
It's regrettably consistent at this very preliminary stage with an insurance/suicide attempt, but no real proof. This should always be at the back of any G/A pilot's mind. Those intending suicide often prioritize their family's welfare (insurance) over the innocent pilots or other pax. It still is a suspected motive in MH370. Very unpleasant either way for the pax's family.
I know of one pax in an Otter many years a go who tried to jump out and nearly succeeded, but was restrained by other pax. After he calmed down they let him go and he made another dart for the door. It turned out to just be extreme claustrophobia, not attempted suicide, but this elderly pax was an experienced pilot.