* Russians face verdict in anti-Putin protest case
* Freed ex-tycoon Khodorkovsky denounces "show trial"
* Defendants charged with rioting, attacking police
By Steve Gutterman
MOSCOW, Feb 21 (Reuters) - A Russian court is expected to jail eight anti-Kremlin protesters on Friday, sending a message that President Vladimir Putin will brook no challenge to his rule as Ukraine burns and casting a shadow over the final days of the Sochi Olympics.
The mother of one of the defendants said the violence in Kiev, where an estimated 67 people have been killed in clashes between security forces and anti-government protesters since Tuesday, increased the chance of a harsh verdict in the trial.
The eight defendants are charged with assaulting police during clashes at an anti-Putin rally on May 6, 2012, the day before he was sworn in for a third Kremlin term after weathering the biggest opposition unrest of his rule.
Kremlin foes blamed the police for the violence at the rally on Moscow's Bolotnaya Square, calling it part of a clampdown on dissent that has included restrictive laws and the jailing of critics such as members of punk protest band Pussy Riot.
Putin tacked back before the Olympics, a major prestige project, engineering the release of two women from Pussy Riot and former oil tycoon Mikhail Khodorkovsky, who was widely seen as a political prisoner after more than 10 years in jail.
But Kremlin critics and relatives do not expect the defendants in the "Bolotnaya case" to walk free on Friday.
"Almost no one doubts that the verdict will be vindictive and cruel," Khodorkovsky, who was flown out of Russia on the day of his release in December, said in a statement on Thursday. He called it a "show trial".
"This trial is a reprisal and an attempt to frighten people," said Stella Anton, whose 21-year-old son, Denis Lutskevich, was dragged bleeding and shirtless from the protest site. He denies hitting police and said officers beat him up.
Anton said she was worried that, with Russia blaming the violence in Kiev this week on protesters trying to oust Ukraine's President Viktor Yanukovich, who is backed by Moscow, the Kremlin would want to send a tough message that violence against police will not be tolerated.
"It seems to me that because of the events in Ukraine, we cannot expect anything good," she said.
Nobody was killed at the 2012 protest and the defendants are not charged with endangering the lives or health of police. One is accused of hitting an officer with an "unidentified hard, yellow object" that his lawyers say was a lemon.
But Putin, a former KGB spy, has said anyone found guilty of attacking police must be punished.
"Unfortunately, I think they'll get real jail sentences," said Boris Nemtsov, an opposition leader. "This trial is absolutely political, the judge is carrying out the Kremlin's instructions."
The Kremlin denies suggestions by its critics that it uses the courts as a political tool.
The defendants - seven men and one woman, most of them in their 20s - are also charged with rioting. By law they could be sentenced to eight years in jail if convicted, though prosecutors have asked for sentences of five to six years.
Prison sentences of any length beyond times served will probably prompt further Western criticism of Putin, already under fire over his role in the Ukraine crisis and over human rights issues such as a new law banning gay "propaganda".
Pussy Riot said that one of the aims of a new video they filmed in Sochi during the Winter Olympics and entitled "Putin will teach you how to love the motherland" was to draw attention to the Bolotnaya defendants.
Anton said she feared no amount of attention would alter her son's fate because she believed "the order has long since been given and everybody knows what the sentence will be."
She said when she last visited her son, they made a pact. "We agreed that whatever the outcome, we will stand tall and hold our heads high. But I don't think I can do it." (Additional reporting by Alexei Anishchuk and Maria Tsvetkova; Editing by Gareth Jones)