
Although the police identify the salesman quickly, Chandrasekhar, like Poirot realise that he cannot have committed the murders.Victor is also manipulated into thinking that he had committed the killings. He is given lists and visits the locations of the murders just before the killings take place.

Rosetti is employed by a (fake) direct sales company.

At the scene of each killing is placed an "ABC" book, although in this case, it is a book which teaches the writing of the alphabet and not a railway guide.However in this case, the letters are signed off as coming from "Z". Each killing is preceded by a letter giving warning of the date and place which are also in alphabetical order. The victims are in alphabetical order.
