A photograph of Billy the Kid  sold for $2.3 million in Denver this weekend, smashing the pre-auction expected price of $400,000.

It is one of the most expensive pieces ever sold from the old West. Billy the Kid’s (real name William McCarty) mother, Catherine McCarty, came from Ireland, as did his father .

The tintype was taken in either 1879 or 1880 in New Mexico. It shows Billy posing with a shotgun, and is is the only authenticated picture of him.

When Pat Garrett, the gradson of Irish immigrints,  finally tracked down and killed Billy the Kid in 1881, a subtext of the killing was the Irish identity of the two famous protagonists.

As Wikipedia notes, little is known about McCarty's origins, but many reputable scholars of western history  "contend that he was born on the eve of the Civil War in the bowels of an Irish neighborhood in New York City at 70 Allen Street."

While his biological father remains an obscure figure, some researchers have theorized that his name was Patrick McCarty, Michael McCarty, William McCarty, or Edward McCarty.

There is clear evidence that his mother's name was Catherine McCarty, although "there have been continuing debates about whether McCarty was her maiden or married name."