Conrad Black, the disgraced British media baron found guilty last July of fraud and obstruction of justice, has begun his prison sentence at a facility in the US state of Florida.
Black will serve a six and a half year sentence after being found guilty of swindling his former company, Hollinger International, out of millions of dollars.
He is being detained at a low security prison about 80km northwest of the city of Orlando in Florida.
Black, who renounced his Canadian citizenship so he could become a British lord, has continued to protest his innocence and is appealing his sentence.
After a lengthy trial, Black was found guilty by a US court in July last year on several counts of fraud for misappropriating about $60 million of shareholders' funds during the sale of Hollinger to the Canadian press group Canwest in 2000, and on one count of obstruction.
His conviction for obstruction of justice was based on a surveillance tape which showed him loading boxes of documents from his office in Toronto into his car despite the US Securities and Exchange Commission (SEC) having informed him he was under investigation.
He was also fined $125,000 and ordered to pay back more than six million dollars in restitution.
The company, which once owned the UK's Daily Telegraph newspaper as well as the Jerusalem Post and Canada's National Post, has since renamed itself Sun-Times Media Group and is currently for sale.
Two other Hollinger executives accused alongside Black who were sentenced at the same time were permitted to remain free pending their appeal.