Leonid Nevzlin, a former top executive of the now-defunct Yukos company, is expected to testify in the High Court in London in a litigation between two Russian oligarchs.
Self exiled tycoon Boris Berezovsky is claiming some $4 billion in damages against Roman Abramovich, who allegedly forced him to sell key assets such as Sibneft and RusAl at knockdown prices.
The hearing started in London on October 3.
Nevzlin, sentenced to life in absentia for multiple murders in Russia and who currently resides in Israel, will testify via a video link from New York on Friday.