(CNN)--There's a tomb at Graceland. There was an autopsy and a funeral and numerous official investigations. There was even a photograph of Elvis in his coffin published in that vanguard organ of American journalism, the National Enquirer.

And yet, for some die-hard devotees, all of that is not enough hard and fast evidence to convince them that the King really met his Maker 20 years ago.

For a dead guy, Elvis sure does get around. He's been seen in a plethora of places, from a Burger King in Kalamazoo to an Hawaiian atoll, where he is said to have established a spiritual retreat with fellow dead-but-not-dead celebrities Maria Callas and Andy Kaufman.

Depending on which witness you believe, he's been hiding out upstairs at Graceland all these years or camping out at ex-son-in-law Michael Jackson's California ranch.

He was even spotted kneeling reverently at the grave of Jacqueline Kennedy Onassis after her death.

Elvis has also been reported holed up in a small unnamed Mississippi town, where he financially supports the entire populace so that they will keep his secret. On a few of the numerous Web sites devoted to Elvis-is-alive lore, there were (tongue-in-cheek?) suggestions that he was seen by Pathfinder on Mars.

That would seem unlikely, given Mars' lack of both oxygen and cheeseburgers. There's no word yet on what he might be offering the Martians for their silence.

Perhaps the only place Elvis hasn't been seen is in Dallas on the Grassy Knoll with a rifle. But then, has anybody really checked the grass for peanut butter-and-banana sandwich crumbs?

The actual source for the belief that Elvis is still alive is hard to trace. But many roads seem to lead back to a Georgia woman named Gail Brewer-Giorgio, who professes to have never even owned an Elvis record until after his death, er, make that "death."

She has written three books on the subject, including a fictionalized novel, published in 1978, in which a famous singer named Orion -- whose life story is strikingly similar to that of the King -- fakes his demise.

After the book came out, a corpulent crooner who sounded a lot like Elvis began appearing around the United States under the name Orion, shielding his identity behind a mask. Some fans concluded Orion was Elvis.

Giorgio followed up her novel with two others, "The Elvis Files" and "Is Elvis Alive?" Together, these books form much of the theoretical gospel for skeptics of Elvis' death.

For example, a 25-member group called the Presley Commission spent more than two years investigating whether or not Elvis was really dead. The group's leader, a Virginian named Phil Aitcheson, said he got interested in the case after reading Giorgio's work.

With a bit of fanfare, commission members unveiled their long-awaited report to the media in 1994, at a camping resort. While members other than Aitcheson chose to remain anonymous, their unmistakable conclusion was that Elvis faked his death.