Image caption The Liberty nickel was kept in a box in a closet for 40 years

A century-old US five-cent coin, once branded a fake, has been sold for $3.1m (£2m) at auction.

The 1913 Liberty Head nickel, one of only five such coins, had a pre-sale estimated price of $2.5m.

The coin's intriguing provenance - it was illegally cast, found in a car crash, deemed a forgery and abandoned for decades - explains its high value.

It was located after a nationwide search and put up for sale by four siblings in the state of Virginia.

"Not only is it just one of only five known, genuine 1913-dated Liberty Head design nickels, this particular one was off the radar for decades until it literally came out of the closet after a nationwide search," said Todd Imhof, vice-president of Heritage Auctions, where the coin was sold.

The nickel was forged at the mint in Philadelphia, Pennsylvania, in 1912 - the final year the Liberty Head was cast - but with the year 1913 cast on its face.

This is one of the greatest coins at that price range Jeff Garrett, Liberty nickel buyer

It is believed that a mint worker named Samuel Brown made the coin, managing to change the die in order to create a coin bearing a bogus date.

The set of coins' existence was unknown until Brown sold them in 1920, and they remained together - although with various owners - until 1942.

A coin collector based in the state of North Carolina, George Walton, had the coin with him when he died in a 1962 car accident. It was found at the scene of the crash among hundreds of coins scattered over the wreckage.

The nickel passed to Walton's sister, Melva Givens, after experts said the odd date on the coin suggested it was a fake.

She placed the five-cent piece in a box containing other family items, where it remained for the following four decades.

The nickel was rediscovered after Givens' death.

In 2003, her children brought it to the American Numismatic Association's World Fair of Money, where the other four Liberty nickels were on display. Experts determined it must be the long-missing fifth coin in the set.

Since then, the nickel has been on display at the association's Money Museum in Colorado.

The coin's new owner, Jeff Garrett of Lexington, Kentucky, said: "This is one of the greatest coins at that price range."

He is understood to have bought the coin in partnership with a man from Panama City, Florida.