Dr. Hans Holzer was the first "Ghost Hunter" I'd ever heard of. He wrote many books on the subject of ghosts, he even investigated a "haunting" in my hometown, Tyler, Texas. His books are very entertaining. One thing I noticed in reading Dr. Holzer's accounts of ghostly encounters was his slow, deliberate approach to his investigations, more like Sherlock Holmes than a live cops reality show.
Below is a 7 part interview with Hans Holzer.