A top economist has fled Russia after being interrogated over the case of jailed oil tycoon Mikhail Khodorkovsky, amid fears that he could be targeted over a report saying that the ex-Yukos chief's conviction was unjust.
The pressure on Sergei Guriyev, the outspoken liberal-leaning dean of the New Economic School, has also raised concerns that investigators may be preparing a fresh case against Khodorkovsky.
In jail since 2003 over fraud and tax evasion, Khodorkovsky was convicted of a second set of fraud charges in 2010 which led to the extension of his jail term.
Guriyev is one of several experts who reviewed Khodorkovsky's case for the Kremlin's human rights council.
Based on the views of the team of experts, including Guriyev's, the human rights council released a report saying that Khodorkovsky's second embezzlement and money laundering conviction was unjust.
The report recommended that investigators reconsider the controversial case against Khodorkovsky.
Over the past months, several experts who worked on the report have faced pressure from investigators and have had their homes searched, said a member of the rights council Tamara Morshchakova.
Morshchakova, a retired Constitutional Court judge, told AFP that investigators claimed that the report was financed with the help of "some foreign money".
Another expert who worked on the report, Mikhail Subbotin, an economist from the Moscow-based Higher School of Economics, told AFP his home was searched in September.
He added that investigators believed the report was written with a certain "agenda" in mind and was financed by Khodorkovsky and his associates.
Guriyev was questioned by investigators more than a month ago in connection with the Yukos case and the report, his lawyer Ruslan Kozhura told AFP.
He said that his client is a witness in the probe and has not been charged.
Guriyev, now in France, said he could not comment on the Yukos case due to a confidentiality oath.
"I can only say that I did participate in the expert evaluation," he told AFP in emailed comments, adding that he believed the report was conducted in an "ethical manner."
"I have never received any money from Khodorkovsky and his partners," he said.
"Better in Paris than Krasnokamensk," Guriyev reportedly wrote on Facebook in a comment that has apparently now been removed. Krasnokamensk is a small town in eastern Siberia where Khodorkovsky served his first term.
Guriyev declined to discuss his personal circumstances and would only say he was on vacation.
A spokeswoman for the New Economic School said Guriyev was on vacation until June 6 and was unaware if he had tendered his resignation.
Guriyev will not run for re-election at the board of directors at state lender Sberbank, a move that the bank's head German Gref called a "huge loss".
Khodorkovsky and his business partner Platon Lebedev have been in prison since 2003 in a case that become a rallying point for Russian liberals who say the former tycoon is being punished for challenging strongman Vladimir Putin.
In 2010, Khodorkovsky and Lebedev were convicted of a second set of fraud charges and are now set for release in 2014.
The interrogation of Guriyev and pressure on other experts have renewed concerns among observers that investigators may be preparing to pursue a new criminal case against Khodorkovsky in a bid to further extend his jail term.
Khodorkovsky's lawyer Vadim Klyuvgant said there were no legal grounds for a new case against his client, but said he could not rule anything out.
"Anything may happen amid this lawlessness," he said.
Subbotin suggested that investigators had acted on orders to "find enough evidence for a third case" against the tycoon.
He said that of six Russian experts who worked on the report, five faced some degree of pressure.
Since returning to the Kremlin for a third term last May despite huge protests against his 13-year rule, Putin has all but dismantled the legacy of his predecessor Dmitry Medvedev and unleashed what critics call an unprecedented crackdown on the opposition.