There was talk about this many months ago and now the evidence has surfaced. According to a recent article, the French newspaper Le Monde published text messages from Philippe Narmino (the minister of justice in Monaco) that show he was working on behalf of Dmitry Rybolovlev.
Rybolovlev has claimed that Yves Bouvier cheated him out of millions of dollars (the number has gone as high as $1billion) by misrepresenting that actual price of the artwork he bought.
It seems that Narmino decided to take early retirement shortly after the article came out. Like they say: rich or poor, it is good to have money. And these guys seem to have a lot!