|Gareth Wyn Williams
Williams, a brilliant mathematician from Anglesey, Wales, worked in Cheltenham for GQHC, Britain's domestic eavesdropping agency. He was living in London on secondment to MI6, Britiain's Secret Intelligence Service, and the block of flats in which his body was discovered was reportedly an MI6 "safe house".
Apparently uninterested in potential national-security angles, the police immediately announced they were looking for clues to Williams' mysterious death in the details of his private life. But they didn't make much headway. A month after his body was found, they still hadn't determined the cause of death, although they had admitted the case was "complex" and "unexplained."
It seemed like a job for Sherlock Holmes and Dr. Watson.
Fortunately, they happened to be available.