Hans Holzer was hunting ghosts before Jay and Grant were even twinkles in their mothers’ eyes.  He will probably be best known for the Amityville case.

His obituary can be read at the Daily Telegraph.

Holzer’s field research, usually conducted with a “trance” medium and a Polaroid camera, led him to the conclusion that “the other side” (a phrase he is said to have invented) is very like this side, only with more red tape. The dead who wish to return to earth have to get permission from “spirit guides”, then wait in a queue and register with a clerk.

If you’ve never read any of his books, do yourself a favor and search them out.