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. Last Updated: 07/27/2016

Thallium Poisoning Found in 2 Americans

Tests reveal that thallium has been found in two American women who were hospitalized last month following symptoms of poisoning, Russian consumer protection service officials announced Tuesday.

Marina Kovalevskaya, 42, and her daughter, Yana Kovalevskaya, 26, were rushed to the emergency room at Sklifosovsky First Aid Hospital on Feb. 24.

Doctors could not immediately identify what was ailing the two women. Further tests revealed traces of thallium, the press office of the consumer protection service told Interfax.

The consumer protection service did not say when or how the women were poisoned.

Moscow's chief public health official, Nikolai Filatov, told RIA-Novosti on Tuesday that the women's condition had improved to the extent that they could leave Russia on Wednesday. Filatov confirmed in an interview that the women had been poisoned with thallium.

A Sklifosovsky doctor, reached Tuesday, said the patients' "condition was not grave but could worsen." He declined to elaborate or give his name.

As of Tuesday, police detectives and prosecutors were still conducting a preliminary investigation to decide whether to start an official probe, said Viktor Biryukov, the Moscow police force's chief spokesman.

Detectives have been investigating those places the two women visited after arriving in Moscow in mid-February from Los Angeles to attend a wedding. These included restaurants and bars.

Detectives have also interviewed people the two women met in Moscow.

A police source told Citi-FM radio late last month that the two women had invited guests up to the Moscow hotel room where they were staying and became ill after the guests left. The women were reportedly staying at the Marriott Tverskaya Hotel on Tverskaya Ulitsa.

Because it takes some time for thallium poisoning to manifest itself, it remains unclear whether, in fact, the women were poisoned in the United States or Russia, the police source said. Investigators are said to be considering working with U.S. law enforcement agents on the case.

The Transportation Ministry told Interfax on Tuesday that it had no plans to check the plane the two women flew on to Moscow.

Police spokesmen refused to comment Tuesday.

A U.S. Embassy official said Tuesday that embassy officials "are in close contact with the family."

In an earlier time, thallium was the poison of choice for some of the communist countries' secret services. Most notoriously, it was used to kill Bulgarian dissident Georgi Markov in 1978.

Former security service agent and Kremlin critic Alexander Litvinenko was initially diagnosed with having been poisoned with thallium. It later turned out that he had been poisoned with polonium-210.

Staff Writer Svetlana Osadchuk contributed to this report.