This story is fairly long and reads rather like the synopsis of a television play, so I suspect that the television script precedes the prose version, although it was broadcast later.
Walter Richmond, young employee of a large bookmaking firm and aspiring tennis player, is sent to find out why a regular customer who has had several big wins has stopped betting. His widow tells him he has drowned, but Richmond suspects he has faked his death. He tracks down the missing husband and tries a little extortion, but he is not the only one on the trail.
Argosy, September 1957.
Televised in the Alfred Hitchcock Presents... series, 1958.