Mrs Ruxton

In the novel One, Two, Buckle My Shoe, Mrs Ruxton was mentioned.

When Chief Inspector Japp and Poirot are discussing the case of the missing Mabelle Sainsbury Seale, Japp says that if she were dead, they would have found the body already. Poirot asks if bodies always come to light so soon, and Japp asks if he is suggesting that Miss Sainsbury Seale has been murdered, and that they will "find her in a quarry, cut up in little pieces like Mrs Ruxton". This suggests that Mrs Ruxton was a victim in a previous case about which Japp knew.