Russia plans to ask Latvia to extradite Russian journalist Alexander Shvarev to face charges of slandering oligarch Alisher Usmanov, Interfax reported Friday.

Authorities in April raided the Moscow offices of Russia’s Rosbalt news outlet, where Shvarev works, in connection with a defamation lawsuit brought by Usmanov. Shvarev is undergoing medical treatment in Riga, according to his lawyer Vladimir Zherebenkov.

An unnamed source told Interfax that Russian investigators are preparing to post an Interpol notice for Shvarev’s arrest in Latvia.

“Shvarev was charged in absentia with libel and extortion. The court will decide on his arrest in absentia Monday,” his lawyer Vladimir Zherebenkov told Interfax on Thursday. In addition to libel, Shvarev is accused of extorting 3.3 million rubles ($51,500) from one of Kazakhstan’s most influential businessmen.

Rosbalt chief editor Nikolai Ulyanov expressed support for Shvarev and dismissed the charges as free speech violations.

A separate defamation case Usmanov won in December ordered a news website to delete three stories alleging the billionaire’s ties with a convicted notorious crime boss. 

Usmanov’s net worth is estimated at between $12.2 billion and $16 billion. Forbes ranks him as the world’s 106th richest man; the Bloomberg Billionaires index ranks him 79th.