Born Philip Schneider, he was an engineer and geologist by trainig, who had worked for the US Government. In the early 90s, he gave presentations at a few UFO conventions. That is where he claimed that he had assisted in the construction of Deep Underground Military Bases that had staff that consisted of both human soldiers and extraterrestrial visitors. He explicitly mentioned meeting Tall Greys who presided some meetings in a secret meeting facility of a UN-like body. Schneider claimed that Tall Greys were the ones who were really in charge of the New World Order
His 1995 MUFON presentation on the topic can be viewed at https://www.youtube.com/watch?v=pT1SnoHxxGo.
Schneider also was the first to speak about a catastrophe and fight at Dulce.
He died a few months after his MUFON appearance in what looks like a staged suicide.
In 2018, Arthur Berkeley published a book on him.