Russian law enforcement raided the offices of a billionaire tycoon whose newspaper published the “Panama Papers,” a series of leaked financial documents detailing the offshore assets and illegal activities of international leaders and members of President Vladimir Putin’s inner circle.

Russia has a history of hitting back at tycoons who challenge the Kremlin. In Thursday’s incident, security and tax inspectors raided Mikhail Prokhorov’s offices at Onexim Group, which manages the 50-year-old businessman’s assets, Reuters reports. Some of the inspectors wore ski masks.

Prokhorov owns the Brooklyn Nets and the newspaper RBC Media. He’s Russia’s 14th richest person, worth $7.6 billion, according to Forbes.

The searches reportedly were associated with suspected tax evasion, a source told Interfax news agency. According to an Onexim spokesman, the company is in full compliance with the law and prepared to cooperate with authorities.

Despite RCB Media’s publication of the Panama Papers, Russians have largely remained nonplussed about accusations that Putin’s friends, particularly leading cellist Sergei Rodulgin, were engaged in an offshore scheme. Putin has publicly defended Rodulgin.

In 2000, masked men raided the offices of media mogul Vladimir Gusinsky as part of a fraud investigation. And in 2004, tax officials raided YUKOS, an oil firm owned by Mikhail Khodorkovsky, a Putin critic. Khodorkovsky was later jailed.

The Associated Press contributed to this report.