The Crewe Circle was a group of spirit photographers based in Crewe, England, in the latter half of the nineteenth century. Led by William Hope, the circle claimed to be able to photograph the souls of the dead. Many psychical research organizations investigated the claims, but the most documented are those sponsored by the Royal Photographic Society and Sir Arthur Conan Doyle, the author of the Sherlock Holmes novels. Conan Doyle was so intrigued by the Crewe Circle that he wrote a book about it entitled The Case for Spirit Photography (1922).
Over the years the spirit photographs taken by the members of the Crewe Circle have come under detailed examination, and have been dismissed as fraudulent by many, but so far none has been proven conclusively to be a hoax. It is possible that the photos could be spontaneous images of spirits captured on the film plates.