In the authorised Miss Marple continuation short story The Murdering Sort, Officer Peter Graves is a member of the Chatham Police Department and a subordinate of Detective Laura Wilcox.
Towards the end of the story, Miss Marple arranged for Graves to be present at the house of Josiah Westover because she feared that the killer would become desperate and kill again. She was right and Graves managed to avert another murder.