Short answers, pulled from the story.
Hans Holzer was an American writer and parapsychologist born in Vienna on the 26th of January 1920 and died on the 26th of April 2009. He wrote more than 120 books on ghosts and the afterlife, hosted a television show called Ghost Hunter, and taught parapsychology at the New York Institute of Technology.
In January 1977, Holzer and medium Ethel Meyers entered 112 Ocean Avenue in Amityville, New York. Meyers claimed the house was built on a Native American burial ground and that an angry Shinnecock Chief named Rolling Thunder had possessed Ronald Defeo Jr., driving him to murder his family. The local Amityville Historical Society denied the burial ground claim, and scholars noted it was the Montaukett, not the Shinnecock, who originally settled the area.
Holzer is sometimes credited with coining the term ghost hunter, which was the title of his first paranormal book, published in 1963. However, Harry Price published a book titled Confessions of a Ghost Hunter in 1936, predating Holzer’s use of the phrase.
Holzer distinguished between three categories: ghosts were environmental imprints detectable by sensitive people; spirits were intelligent beings that could interact with the living; and stay behinds were those who remained earth-bound after death. He also believed in reincarnation and in levels of consciousness.
An article in the Journal for the Society for Psychical Research cast considerable doubt on the objectivity and reliability of his work. Skeptical investigator Joe Nickell wrote that Holzer credulously accepted spirit photographs, anecdotal reports, and other doubtful evidence without adequate verification. Holzer’s endorsement of psychic archaeology was also widely criticized as pseudoscience.
The Holzer Files is a Travel Channel series that began in 2019, a decade after Hans Holzer’s death. The show sends current ghost hunters back to locations that Holzer documented during his career.