Billy the Kid photo snapped up for $2 million by William Koch

Big pic below.

The only known photo of Billy the Kid was predicted to sell for $300,000 to $400,000 at the 22nd annual Old West Show & Auction in Denver tonight. But the circa 1879 tintype went for five times that in spirited, and speedy, bidding that ended at $2 million.

That's because William Koch, listed byForbes as having a net worth of upwards of $3.5 billion, was determined to snap up Billy the Kid.

William Koch, who owns Oxbow Corp., lives in Florida but has property in western Colorado. And he wasn't the only Koch brother in the state this weekend: His brothers Charles and David Koch, who run the privately held energy giant Koch Industries, are hosting a confab of conservatives outside of Vail this weekend.

But while his brothers were hobnobbing with politicos at an event that's already drawing protests, with more action planned for tomorrow morning, William Koch was sitting in the crowd at the Denver Merchandise Mart, waiting for the auction to make its way through the beaded moccasins and Buffalo Bill artifacts for lot #279, the photo taken of William Bonnie, aka Billy McCarty, aka Billy the Kid, outside a bar in Fort Sumner, New Mexico, by a traveling photographer. Billy gave one of the four photos from that session to Dan Dedrick, a cohort, and it had been in the possession of the Dedrick family ever since. (One of the other copies was destroyed in a fire; the other two have never been found, according to the auction catalogue.)

"You're going to be a part of American history tonight," the auctioneer had promised the audience before he started the bidding for the Billy the Kid photo.

And William Koch didn't just buy a piece of history; he made history with his record-shattering bid -- which ran about $400,000 a square inch.

The total cost of the tintype image was $2.3 million after fees were paid to the auction house.

Courtesy Brian Lebel's Old West Show & Auction

For more wild West action, read Patricia Calhoun's "National Western Stock Show subject of a range war between Denver and Aurora."