An 18th century British painting stolen by mobsters in 1969 has been returned more than half a century later to the family that bought the artwork during the Great Depression, the FBI has said.

The John Opie painting — titled The Schoolmistress — is the sister painting of a similar work housed in the Tate Britain art gallery in London.

Authorities believe the Opie piece was stolen with the help of a former New Jersey politician then passed among organised crime members for years before it ended up in the southern Utah city of St George.

A Utah man had purchased a house in Florida in 1989 from a convicted mobster and the painting was included in the sale.

When the buyer died in 2020, a Utah accounting firm that was seeking to liquidate his property sought an appraisal for the painting and it was discovered to likely be the stolen piece, the FBI said.

The painting was taken into custody by the agency pending resolution of who owned it and returned on January 11 to Dr Francis Wood, 96, of Newark, the son of the painting’s original owner, Dr Earl Wood – who bought it during the 1930s, the FBI said.

Opie was a British historical and portrait painter who portrayed many people, including British royals. His paintings have sold at auction houses including Sotheby’s and Christie’s, including one that sold in 2007 for almost one million dollars.

According to the FBI, The Schoolmistress was taken from Earl Wood’s house by three men working at the direction of former New Jersey state Senator Anthony Imperiale.

But the claims against the state lawmaker, who died in 1999, were not sufficiently corroborated and he was never charged, the agency said.

Authorities say the men broke into the house in July 1969 in a bid to steal a coin collection, but were foiled by a burglar alarm.

Local police and Mr Imperiale responded to the attempted burglary, and the home’s caretaker told the lawmaker that the Opie painting in the home was “priceless”, the FBI said.

The men returned to the house later that month and stole the painting, the FBI said, adding that one of the men later admitted to the theft and testified that they had been acting under Mr Imperiale.