For example, the following cases:
1. El primer teniente Felix Eugene Moncla Jr.
He was a U.S. Air Force pilot who was sent by plane to intercept an air defense over Lake Superior, on the border with Canada, in 1953. According to official reports, he left Kinross Air Force Base to intercept an aircraft that had strayed off course, however… the Canadians had no record of any aircraft in the area that night.
Radar operators reported receiving one light signal, then a second; then the two merged. After that, no trace of the Moncla F-89 jet was recovered, neither on land nor in the lake; it simply vanished. The theory that circulated widely was that it had encountered a UFO.
2. Ray Gricar
In April 2005, this man, a Pennsylvania district attorney, called his girlfriend to say he was going for a drive and would be back soon. He never returned. His car was found parked outside a nearby antique shop, while his laptop was discovered in a local river. There was never any sign of him, and it is unknown whether he was kidnapped and murdered because of his high-profile job.
3. Kenny Veach
In November 2014, Veach disappeared while trying to find a hidden cave. In a comment on a YouTube video, he mentioned that he accidentally found an "M"-shaped cave in the Nevada mountains near Nellis Air Force Base. He posted that upon finding it, he was so frightened that he ran away, unable to remember the location.
A month later, he left another comment on the same video, stating that he was going to go looking for the cave again. That was the last anyone heard from him.
4. Rebecca Coriam
In 2011, Rebecca was working on the Disney Wonder cruise ship, which departed Los Angeles en route to Cabo San Lucas, Mexico. In the middle of the ocean, Rebecca failed to show up for her 9:00 a.m. shift. When the staff went to her cabin, she was gone. The only evidence of Rebecca's disappearance was a large amount of surveillance footage showing her on the phone, and then nothing more—she simply vanished. The ship returned to its course, and the Coast Guard conducted a search, but found no trace of her. Her parents had to accept the fact that she had mysteriously disappeared. But then things got even stranger…
Weeks after her disappearance, someone changed her Facebook password and tried to access her bank accounts. Then, a former coworker told her parents that the cruise line had instructed them to deny that her disappearance had occurred.
5. Conor and Sheila Dwyer
This is one of the most mysterious missing persons cases in Irish history. An elderly couple, Conor and Sheila, attended a funeral mass in the town of Fermoy. Afterward, they got into their car and presumably drove home… but they never arrived.
After a few weeks of not hearing from them, Sheila's sister went to their house and found the door locked. Inside, all their belongings were untouched (clothes, passports, money, etc.); the only things missing were the clothes they had been wearing that night and their car.