Just a week ago Florian Homm was speaking on Germany's national Channel 2 station, ZDF. Now he is in detention and facing deportation to the United States, the paper wrote, saying it obtained some of its information from the Ansa Italian news agency.
In the US the Securities and Exchange Commission is seeking $56 million for €44 million from Homm, who is also facing criminal charge in Los Angeles carrying penalties of up to 75 years in jail.
Only last week Homm, who is the great nephew of catalogue sales giant Josef Neckermann, was speaking in a relaxed manner with Left party leader Sahra Wagenknecht in a talk show on the ZDF television station.
He was visiting a museum near Florence on Friday with his ex-wife and son when police found him, the newspaper said on Saturday.
News agencies reported that the tip about Homm's whereabouts came from the FBI, which relayed it to the US Consulate in Milan.
Conspiracy and fraud charges are awaiting him in Los Angeles, where he is reported to have swindled investors using a sophisticated scheme that artificially pushed up the price of worthless stocks.