By the end of chapter 14 who is missing and what "clue" is given to lead the others to believe he/she is dead?

A few minutes go by, and Vera amuses herself by trying to imagine how Armstrong might burst his way in through her door. She hears the breaking of glass downstairs, and then Blore knocks on her door. She opens it to find both men. They tell her that Armstrong has disappeared. They think that he has vanished off the island, like some “conjuring trick.” Lombard adds that a windowpane is busted downstairs and that another of the Little Indian Boys has been smashed.