A probe was launched into Bilal Erdogan after Italian authorities were petitioned by Turkish businessman Murat Hakan Uzan - an exiled political opponent of Erdogan - to investigate a purported "getaway operation" from Turkey to Italy.
Erdogan's son moved to Bologna in August to complete his doctoral studies, but was accused by anti-government parties of fleeing his homeland after being implicated in a corruption scandal.
Bilal, who lives in the north Italian city with his wife and two children, insisted he was merely winding up his PhD in international relations at the School of Advanced International Studies at Johns Hopkins University.
The 35-year old was one of the main protagonists implicated in corruption allegations that exploded in December 2013 against the president's inner circle and were bitterly denied by Erdogan, then premier.
Leaked tapes emerged in February 2014 of Erdogan allegedly telling Bilal to dispose of some €30 million ($37 million) in cash.
Erdogan has dismissed the recordings as a "vile montage".
Uzan's petition stated that Bilal flew into Italy with a "large sum of money" and a team of armed bodyguards who were denied entry before swiftly being assigned Turkish diplomatic passports, according to Italian media reports.