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The 2017 beating of a Russian prisoner, seen in a shocking video released last week, is being investigated in detail, the head of Russia's delegation told the U.N. Committee Against Torture on Thursday.

Mikhail Galperin told a committee session in Geneva that Russia's firm response to the incident, which has sparked wide public concern, could discourage future abuses.

A video released last week by the Novaya Gazeta newspaper shows Evgeny Markov, an inmate at a prison in the Yaroslavl region, being beaten by men in guards' uniforms while lying handcuffed on a table. The shaky video is believed to have been taken by a guard's body camera.

Six guards have been ordered held in detention for two months while the 2017 beating is investigated and the prison's deputy chief is also being held.

Yet the lawyer who obtained the video has fled Russia because of concerns about her security.

"I don't plan to come back to Russia yet, because I want to see how this case will go," Irina Biryukova told The Associated Press on Wednesday.

The video showed more than 10 guards involved in the beating and Bitukova expressed concern that not all suspects had been arrested.

After the video was released, "I started receiving threats as personal messages," she said from an undisclosed location.

She said she was appalled by the video.

"When I opened the file for the first time, I could only watch the first 10 seconds without sound and didn't manage to watch anymore," said Biryukova, who works the Public Verdict Foundation human rights group. "Then we all watched it together and decided that it definitely needed to be published without sending it to the investigative authorities first, because that wouldn't yield any results."

Galperin, the Russian envoy to the UN torture committee, expressed "confidence that the investigation of this incident, bringing it to court and the severe punishment of those found guilty, without any consideration for rank and position, should become and I am sure will become, a clear signal about the inadmissibility of torture, the inadmissibility of violations of Russian law."

But activist Anastasia Garina of the Committee Against Torture said she doubted the case would bring about significant change in Russia.

"While attention is focused on this problem, something will happen ... and then everything will settle back down again," she said. "We won't just wake up one day in a different country just because this video was leaked."

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Jim Heintz in Moscow contributed to this story.