Or could there be conspiracy theories at play?
What is "mysterious" about drownings or drug overdoses? Apart from the one disappearing girl that the OP references, which deaths have been "unexplained" as opposed to nothing more than "we don't like that explanation"?
Perhaps the deaths that are determined to have been accidents were just accidents?
Sad, indeed, but the family have not made any mention about any "mysterious" or "unexplained" circumstances in the case of the Irishman.