India, March 9 -- The disappearance of retired Air Force major general William Neil McCasland, who has deep expertise about UFOs, constitutes a "grave national security crisis," an investigative journalist has said. McCasland, 68, went missing on February 28 after leaving his Albuquerque, New Mexico, home on foot, per the New York Post. Left his phone behind.

A missing persons investigation is underway. The FBI has joined the probe.

"This is a man with some of the most sensitive secrets of the United States in his head," journalist Ross Coulthart said in the latest edition of his 'Reality Check' podcast.

He claimed that McCasland may even know what the US government might be hiding regarding extraterrestrials.

The Bernalillo County Sh...