UK businessman Derek Bond was arrested in South Africa at the request of FBI officials investigating fraud in the US.
Mr Bond is described as a quiet man
The father-of-three and his family insisted all along it was a case of mistaken identity.
But the FBI initally insisted he is Derek Sykes, wanted in connection with a telemarketing scheme which defrauded people of millions of dollars.
Only on Wednesday did it emerge the real Mr Sykes had been arrested in Las Vegas.
Mr Bond is a retired charity worker who worked for the Rotary Club in Clifton.
Bill Hardyman, 76, Mr Bond's best friend, said he had known him for more than 40
years and described him as "a man of great honour".
Mr Hardyman said: "He's obviously very low and we're worried about him but we certainly are not
worried on the grounds that there's any truth in any allegations."
Keith Nepean, president of Clifton Rotary Club, also has a 40-year friendship with Mr Bond, who helped to found the club.
He said the allegation was "ludicrous" and added: "He's extremely honest. He has a lot of friends. He is a very helpful person,
involved with charity work as well as being an astute businessman.
"He is a truly nice person. It does not fit with the description from the FBI."
Mr Bond's son Peter, 45, from Peterborough, Cambridgeshire, said his father had suffered a chest condition after his arrest.
He had recovered his health and was now determined to clear his name, he added.
Peter Bond said identity fraud was probably behind the mix-up and someone had obtained details of his father's identity to use fraudulently.
Derek Sykes: the man the FBI are pursuing for fraud
Mr Bond's sister Gillian told the Mirror newspaper: "He is a quiet, 72-year-old man with high blood pressure."
On Tuesday, the Interpol website carried an image of a Derek Lloyd Sykes on its "wanted" page.
Mr Sykes is the same age as Mr Bond, according to the website.
It says he was born on 26 January 1931 in Britain, has blue eyes, weighs 160 pounds and stands 1.77 metres tall (5ft 8in).
But the family denied the photograph on the Interpol website was Mr Bond.