As reported by Censor.NET citing the Financial Times, 76-year-old neo-Nazi Istvan Gyorkos's was taken into custody and faces possible charges after police officers came to his house in late October in search of illegal guns and one of them was shot dead.
While Russian support for far-right groups in Europe has been widely rumoured, the recent events in Hungary have brought to light new evidence of Moscow's long-running attempts to cultivate far-right extremists.
He was known nationally for his fascist political views and, in his home town of Bony, the MNA staged regular paramilitary drills in the muddy hills behind his house and even invited townspeople to watch.
What was less well known was the far-right militia's multiple ties to Russian secret services.
Most significantly, Hungary's national security committee has since confirmed that the MNA's members openly trained with Russian diplomats and men dressed in Russian military intelligence uniforms.
Emails exchanged between MNA leaders and obtained by Hungarian media reveal a strategy to secure funding from Moscow. Mr Gyorkos also founded Russian-domain website Hidfo.ru, a forum for pro-Russian disinformation on Ukraine's war.
A person familiar with the links between Russia and the far right said the MNA - founded in 1989 and one of about a dozen extremist far-right groups in Hungary - was attracted to Russian intelligence by Moscow's anti-western, anti-globalisation ideology and the uncertain prospect of financial support.
Analysts question why Hungary's government allowed Russian agents and Hungarian militants to openly co-operate on Nato territory over several years without intervening. Almost uniquely among countries in its neighbourhood, Budapest has not expelled any Russians individuals suspected of espionage in the past six years.
The frustration is shared by some in the Hungarian security services. Two people familiar with internal tensions said Russian support to militants had been known for years but the government's strong political links with Moscow and fears of an economic backlash had prevented any response. Those links include Hungary's heavy reliance on Russian gas and the €10bn in Kremlin funding to build two Russian-designed nuclear reactors in Paks, by far the largest investment in Hungary in years.
Prime minister Viktor Orban, who enjoys cordial relations with Russian president Vladimir Putin, has been among the vocal opponents of E.U. sanctions on Russia and says co-operation with Moscow is imperative for Hungarian national interests.
Zsolt Molnar, an opposition lawmaker and chairman of Hungary's national security committee, said the killing was a "wake-up call" for Hungarian intelligence services who underestimated the lethal dangers posed by the MNA. But he played down the international significance. "The killing wasn't ideologically motivated," he said. "It's not necessarily appropriate to make this into a diplomatic issue."
Hungary's government agrees, at least for now. Peter Szijjarto, Hungary's foreign minister, said he would await a full report from authorities before making any formal diplomatic complaint. "When you want to express concerns to Russians you have to base that on strong information and strong wisdom," Mr Szijjarto said. "It's not a strong position otherwise."