Freeman Wills Crofts, The Cask — Chapter 16 (1920)
“ A former lover, he thought. So far they knew of none, and Burnley took a mental note that inquiries must be made to ascertain if such existed. Failing a former lover, the husband immediately came into his mind, and here he seemed on firmer ground. If Madame had had an understanding with Felix, and Boirac had come to know of it, there was the motive at once. Jealousy was what one would naturally expect Boirac to feel under such circumstances. There was no doubt that, so far as the facts had as yet come to light, Boirac’s guilt was a possibility they must not overlook. ”
