Dyer

In the short story The Lost Mine, Dyer was one of two passengers which Wu Ling had associated with while on a ship from the Far East to Southampton. When Mr Wu Ling was found murdered, Dyer became a suspect. He was a "broken-down European" with a somewhat unsavoury reputation and known to be involved with a gang of Chinese crooks. However, Dyer was able to provide a watertight alibi.

Portrayals
Dyer was played by James Saxon in the film adaptation of the story in episode 3 of Series 2 of ITV's Agatha Christie's Poirot drama series. In the episode, he is given a slightly more detailed background. He had the first name Reginald or "Reggie" which was not given in the original story. He had twice been convicted of currency fraud and had been seen associating with Wu Ling on board the ship from the Far East. He was arrested with a suitcase full on money in Chinatown after extensive vehicle surveillance by Scotland Yard. His lawyer managed to get him released but he was later arrested again in a Chinatown opium den and charged with smuggling opium.