Monaco police detained billionaire collector Dmitry Rybolovlev in connection with a $1 billion art fraud dispute.

Dmitry Rybolovlev, the Russian fertilizer billionaire and soccer club owner, was detained by Monaco police on Tuesday as part of an investigation into alleged influence-peddling and corruption related to his globe-spanning legal feud with Swiss art dealer Yves Bouvier. Police also searched Rybolovlev’s lavish Monte-Carlo penthouse, La Belle Époque, on Tuesday morning, according to Le Monde.

Rybolovlev, who alleges that Bouvier overcharged him by about $1 billion in the sale of 38 artworks over the course of more than a decade, is suing the Swiss art dealer in Monaco, Singapore, and France. Bouvier and Sotheby’s are suing the Russian tycoon in Switzerland; and just last month Rybolovlev filed a $380 million lawsuit against Sotheby’s in New York.

For more than a year now, a judge has been investigating claims that Rybolovlev tried to influence Monaco’s authorities in connection to the Bouvier affair. In September, the head of judicial services for Monaco, Philippe Narmino, resigned after Le Monde published a report showing alleged links between Rybolovlev and justice officials in the principality. Asked about the investigation, the Russian billionaire’s attorneys told Reuters: “We request that the presumption of innocence in relation to Mr Rybolovlev is strictly respected.”