Pretrial hearings into Politkovskaya's killing began Wednesday at a Russian military tribunal, but Moskalenko was unable to be there as she was ill.
Anna Stavitskaya, another lawyer representing the Politkovskaya family, said the mercury might have been part of an attempt to intimidate Ms. Moskalenko.
In New York, the Committee to Protect Journalists said it was “deeply concerned” about her welfare, citing news reports saying Ms. Moskalenko “was the target of an apparent poisoning in Strasbourg” and “had felt weak for several days.”
Ms. Moskalenko spends much of her time in Strasbourg, in eastern France, pursuing cases at the European Court of Human Rights, according to the radio station. Some of her cases have been on behalf of Chechens complaining of human rights abuses. She has represented Mikhail B. Khodorkovsky, the jailed oil tycoon. According to the Committee to Protect Journalists, Ms. Moskalenko’s clients included Garry Kasparov, the former chess champion who has become an opposition political leader in Russia, and Mr. Litvinenko, the former K.G.B. officer.
At the hearing in Moscow, a judge refused a request by lawyers for Ms. Politkovskaya’s family that the session be delayed because of Ms. Moskalenko’s illness.
Two Chechen brothers, Dzhabrail and Ibragim Makhmudov, are accused of conducting surveillance of Ms. Politkovskaya. A former police officer, Sergei Khadzhikurbanov, is accused of providing technical help. All three deny the charges.
Ms. Politkovskaya’s supporters argue that a third Chechen, suspected of shooting her, is on the run.
The court failed to decide whether to allow news media access to cover the trial, which is being held at a military court in Moscow, the authorities say, because of Mr. Khadzhikurbanov’s former ties to law enforcement.
Ms. Stavitskaya said that while she would like the trial to be opened to journalists, she did not think the court would allow it.
“They have no basis for closing the trial,” she said. “We want this to be accessible to the people, so that they can reach their own conclusions.”
The next hearing is set for Nov. 17, with jury selection scheduled for the following day.