Wolfang Kroll, 57, appeared in a court in Rome along with three accomplices last week, according to Italian newspaper 'Corriere della Sera'.
The group is accused of tricking the German businessman out of 1.3 million euros in 2008, in a series of fake business deals to buy key buildings in Rome.
Kroll, also German, presented himself as a real estate broker and allegedly approached the businessman, offering to sell him the Porta di Roma shopping centre, 'The Local' reported.
The duo then took the help of Walter Baccini, who impersonated a government official, and Anna Lisa Morganti to 'sell' the US embassy building in Via Veneto, and the headquarters of the UN food agency, Food and Agriculture Organization (FAO), in Viale delle Terme di Caracalla.
The price of the embassy was set at 580,000 euros, while FAO was supposedly on sale for 600,000 euros.
The German businessman transferred a further 900,000 euros to the group, before realising he had been tricked.