The members of the Tuesday Club debate possible solutions between them but Miss Marple hits on the correct one: although she does not know what caused Sir Richard to stumble – possibly a trip over a tree root – it was his cousin Elliot who quickly stabbed him in the pretence of examining him. The knife was hidden as part of his fancy dress costume.
Dr Pender confirms that five years later, Elliot wrote to him on the eve of an expedition to the South Pole admitting the crime and the torment he has suffered since. His motive was love for Diana Ashley, and by killing his cousin he both removed a rival and inherited his wealth.