A man who took a dead baby's name and used it for more than 20 years, could be the missing son of an American family who last saw him in 1983.
Christopher Buckingham was held after arriving in Dover by ferry
Christopher Buckingham, 43, assumed his stolen identity the same year and lived for two decades as a bogus aristocrat.
Kent Police said the claim made by the Stopford family in the US was a "promising development".
Buckingham was jailed for 21 months in late 2005, reduced to nine on appeal, after he falsely obtained a passport.
Fake documents, including headed notepaper bearing the Duke of Buckingham's coat of arms, were found in his car when he was arrested by Kent Police in Dover.
He pleaded guilty at Canterbury Crown Court to making an untrue statement for the purpose of obtaining a passport.
Now Charles Stopford has told a Sky One television programme he is "100% positive" the mystery man is his son.
"I've seen the photos and I know it is him," he said.
Kent Police are in contact with the Stopfords to try and verify the family's claims.
A statement said: "This is a promising development but until we have obtained firm evidence of Christopher Buckingham's true identity it would be wrong to leap to any conclusions.
"Kent Police is in contact with Interpol and the United States authorities and is working to obtain fingerprint and DNA checks."
The real Christopher Buckingham was born in 1962 in Lambeth, south London, but died in West Sussex the following year.