I would agree that family letters should be given more weight than press accounts, but it's still quite possible for people to recall what they think they should have seen instead of what they actually did see. Person hears a gunshot. Person sees an officer's head vanish below the crowd in the (remember, very dim) light of the deck. Person hears a report through the crowd that an officer has shot himself. Memory suddenly adds details like a gun coming to the officer's head and blood coming from a wound that simply weren't there. It happens all the time with eyewitnesses, unfortunately, and in this case we can't sit the witness down and ask the "what did you actually see -- with no interpretations" question.
Since there were survivors who were nearer to our various "likely candidates" who saw nothing, I remain skeptical. Not an out-and-out denier, of course. If we could invent the time window and look back at that night, I would not be surprised to learn that those accounts were accurate. However, I consider it more likely that we've got unreliable witnesses.