Artefacts connected to some of America’s most notorious gangsters have sold for more than 100,000 dollars (£78,000) at auction.

A diamond pocket watch that belonged to Al Capone, produced in Chicago in the 1920s, and a handwritten musical composition he wrote in Alcatraz in the 1930s were among the items sold at the Gangsters, Outlaws and Lawmen auction.

The watch fetched the most — 84,375 dollars (about £66,000) — according to Boston-based RR Auction.

The winning bidder for the watch was not identified. The buyer is a collector who has an eye for interesting US artefacts, said RR Auction executive vice president Bobby Livingston.

He was among about 30 internet, telephone and in-person bidders.

Capone’s musical piece, entitled Humoresque, sold for 18,750 dollars (£14,600).

The piece shows Capone’s softer side, including the lines: “You thrill and fill this heart of mine, with gladness like a soothing symphony, over the air, you gently float, and in my soul, you strike a note.”

Mr Livingston said he was not surprised that lyrics written by a man better known for organised crime than his musical talents sold at the auction because of the way Capone “resonates in the American imagination”.

“The musical artefact gives insight into who this man was,” Mr Livingston said. “It humanises him and shows that he had an imagination and creativity. These people had talents and they used those talents, unfortunately for criminal endeavours.”

He was referring not just to Capone, but to infamous couple Bonnie and Clyde.

An autographed “So Long” letter written by Bonnie Parker and signed by Clyde Barrow just before their deaths sold for 16,250 dollars (£12,700). A pair of Texas arrest warrants fetched 8,125 dollars (£6,350).

Parker’s silver-plated, three-headed snake ring fetched 25,000 dollars (£20,000).

The ring was not made by Barrow— a skilled amateur craftsman who engaged in jewellery making, woodworking and leathercraft behind bars — as originally believed, according to RR Auction’s website.

Barrow’s nephew Buddy Barrow and Parker’s niece Rhea Leen Linder were at the auction.

“I asked Buddy Barrow what his uncle would be thinking about the auction, he felt that Clyde would have said, ‘make as much money as you can’,” Mr Livingston said.

A letter written by John Gotti, the reputed head of the Gambino crime family in New York, did not sell. The 1998 letter to the daughter of a mob associate urges the recipient to tell her father “to keep the martinis cold”.