Dmitry Sotnikov, a lawyer for the jailed man, told AFP that the case was fabricated and that his client was beaten and starved in the jail in Simferopol after being detained in February.
Prosecutors said Alexander Kostenko, a resident of Crimea, was found guilty of "inflicting physical harm" on a riot police officer during the protests despite arguments from his lawyers that the court on the Russian-annexed peninsula had no jurisdiction to try events that allegedly happened in Ukraine.
A statement on the Crimea prosecutor website said former police officer Kostenko was also found guilty of later storing firearms in his home.
The court sentenced him to four years and two months in a penal colony.
Mass protests in Kiev in the winter 2013-2014 ended with the toppling of Kremlin-backed president Viktor Yanukovych's last February.
Moscow seized Ukraine's Crimea region in the wake of Yanukovych's ouster in a move that sent ties between Russia and the West plummeting to their lowest point since the end of the Cold War.
Crimea's Moscow-loyal prosecutor Natalia Poklonskaya accused Kostenko of yelling Nazi slogans, doing the Hitler salute and participating in "Gestapo" torture during the Maidan protests in Kiev as she turned his trial into a condemnation of the authorities in Kiev.
Russia portrays the ouster of Yanukovych in Kiev -- during which some 100 protestors were gunned down -- as a far-right coup that justifies its seizure of Crimea and political backing for separatists fighting government forces in east Ukraine.
Kostenko's lawyer Sotnikov dismissed the claims and said the prosecutor "could only say this under the influence of heavy drugs."
Sotnikov said Russia's federal security service (FSB) operatives broke Kostenko's arm during interrogation after snatching him from the street outside his house on February 5 and denying him hospital treatment.
The first time he saw his client, Kostenko "came out covered in bruises and blood and asked: 'Take me away from here'," the lawyer said.
"There are fabricated cases in Russia, but rarely such humiliation and physical harm," he said. "A living person is being tortured for a political idea, to be able to boast winning over fascism."
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