Transfer dealings in Italy have been put under the microscope after prosecutors began investigating Juventus' accounts in what is claimed to be a system of player trades at allegedly inflated values in order to help balance clubs' books.
AFP looks at why the probe was launched and what it could mean for Juve and Italian football as a whole.
Why are Juve being investigated?
Juve are being probed over €282 million ($319m) of capital gains - the positive difference between purchase and sale values net of amortisation and write-downs - from a series of player transfers booked in their last three sets of annual financial results, the latest of which were published in September.
Prosecutors in Turin are investigating the possibility that Juve, who are listed on the Italian stock exchange, presented false accounting information to investors and produced invoices for non-existent transactions over that period.
Also under investigation are six current and former directors, including chairman Andrea Agnelli, vice-chairman and former player Pavel Nedved and ex-sporting director Fabio Paratici, who is now at Tottenham Hotspur.
A raft of transfers involving Juve and other clubs are also the subject of a parallel investigation which was launched by the Italian Football Federation (FIGC) in October.
A source from Italian football's supervisory commission COVISOC told news agency ANSA that since autumn last year it has identified dozens of such deals.
The one which took Victor Osimhen to Napoli last year stands out as it involved four players valued at just over 20 million euros moving to Lille. Three of them never played for the French club and are now in Italy's lower divisions.
How do these deals work?
The deals being investigated are those between clubs in which two players change hands but there is relatively little or no money going in either direction.
The most cited example in the reported 42 suspicious Juve transfers being looked at by the FIGC is last year's deal between the 36-time Italian champions and Barcelona which saw Miralem Pjanic move to Catalonia and Arthur Melo go the other way.
Arthur was valued at €72 million and Pjanic €60 million, but even though nowhere near that amount of cash was paid both clubs could immediately book the values of the sales on their balance sheets.
Clubs can spread the cost of a player purchase over the length of their contract in the form of 'amortisation' while capital gains from sales appear on that year's accounts. Juve recorded a capital gain of €43 million on Pjanic, the second highest in the club's history.
The expensive purchase of Cristiano Ronaldo in 2018 was followed by a spike in such operations, largely involving younger players of whom most fans have never heard.
What punishment could Juve face?
Speaking in daily Corriere Dello Sport on Wednesday, lawyer Salvatore Scarfone said that it is difficult "to prove intentional inflating of player values", which according to Italian media is a sort of open secret within the football industry.
However as well as documents taken from Juve's offices last weekend, the criminal prosecution of the club is also reportedly based on wiretapped conversations.
What is discovered by prosecutors will then be passed on to the FIGC, which has powers to sanction clubs with a range of punishments from fines to being kicked out of the league.
The most recent case led to Chievo being docked three points in September 2018 for false accounting on exchanging players with Cesena. They were relegated that season and went bust earlier this year.
A decade earlier AC Milan and Inter Milan were acquitted in criminal proceedings after a probe into swap deals between the two clubs but given a small fine by the FIGC.
Rule change incoming?
With the true value of a player notoriously hard to pin down, what can be done to curb the worst excesses of what is a entirely legal accounting move?
FIGC chief Gabriele Gravina said on Wednesday that football authorities in Italy have been working on the issue for "two to three years".
"We need to work out if we can adopt criteria which take into serious consideration actual capital gains that are linked to money changing hands. We're working on it," Gravina said.