Who is Walter Dew from Thunderstruck and what is their importance?

Chief Inspector Walter Dew took part in the Jack the Ripper case, and he is the primary investigator in the Crippen case. Dew initially doesn't suspect foul play, and his first search of the Crippen home uncovers no tangible evidence. He is alarmed, however, by Crippen's disappearance and circulates a flyer containing descriptions of both Crippen and Ethel. When he learns about Kendall's suspicions on board the SS Montrose, Dew boards a fast ship, traveling as "Dewhurst." He succeeds in intercepting the fugitives when they arrive in Canada, and escorts them back to England on another ship.