I read his book "Mothman Prophecies" when I was younger. I made the mistake of doing so at night, and every little noise made me jump.
The man wrote a great book about a subject that was ridiculed by many. He was courageous to do so, and has a legion of fans who were turned on to UFOs and the paranormal. He will be missed by us and mainly that young man reading his book at night!
Rest in peace and may the Goddess bless you, John Keel.