Napoli president, Aurelio De Laurentiis, is being investigated for possible fraud in the transfer.
The deal has long been the subject of controversy, as the official €70m transfer plus €10m in bonuses fee was only circa €50m in cash.
The other €20m was made up of goalkeeper Orestis Karnezis and three youth team players Luigi Liguori, Claudio Manzi and Ciro Palmieri.
The value of Liguori, Manzi and Palmieri immediately raised eyebrows, because they were given highly inflated prices on the transfer market.
There was even more controversy as the three players never got to wear the Lille jersey, as they were immediately loaned out to Serie C sides and their contracts were simply terminated a year later free of charge.
The players went to the media complaining the deal had ruined their careers and they were used as pawns in a larger transaction used to bolster the finances of both Napoli and Lille.