Rasul Mirzaev, 26, walked free from court on Monday after being convicted of killing a student in a case that highlights Russia's fraught ethnic tensions.
Mirzaev received the maximum sentence of two years in prison for causing death by negligence over the incident outside a Moscow nightclub last year, but was released immediately because of time already served.
Mirzaev's release is likely to anger nationalists who complained when more serious charges were dropped earlier this year, and has revived memories of race riots in downtown Moscow in 2010 that followed the fatal shooting of a football fan by a migrant from the country's North Caucasus region.
The case captivated Russia and focused debate on relations between ethnic Russians and people from the North Caucasus, many of whom, including Mirzaev, have moved to Moscow since the collapse of the Soviet Union.
Many Russian nationalists protest the huge government subsidies allocated to the impoverished Caucasus, where unemployment is high.
Nineteen-year-old Ivan Agafonov died after Mirzaev hit him with a single punch to the face, causing the student to fall and strike his head on a metal drain cover.
The two had argued after Mirzaev accused Agafonov of insulting his girlfriend. Agafonov’s friends have said he merely shared a joke with Mirzaev’s girlfriend.
The fighter, known as the Black Tiger, originally faced a sentence of up to 15 years before the charges were reduced in January. Mirzaev pled guilty to the lesser charge of causing death by negligence, saying there was no intent to harm Agafonov.
Lawyers for Agafonov’s family have accused the prosecutor of ignoring their interests and earlier vowed to seek harsher punishment for Mirzaev at the European Court of Human Rights if he were to be convicted of the lesser charge.
Agafonov's mother was hospitalized Tuesday morning after suffering a heart attack. His father stormed out of the courtroom before the sentence was read out.
Ethnic-Russian nationalists protested outside the court, with Dmitry Dyomushkin, the head of the "Russkie" movement, arrested as he attempted to enter the court along with three others.
Mirzaev was a world champion in the Russian martial art of sambo, and had been due to fight in Bellator before the incident.