“Any political exploitation and speculation without knowing the backgrounds should be rejected. The international community should help to uncover and reveal the true backgrounds," Andrej Hunko from the leftist Die Linke party told Sputnik.
Hunko said that the crime seemed to be professionally and politically motivated, but the true reasons are yet to be found.
Boris Nemtsov, who served as Russian deputy prime minister and energy minister in the 1990s and later turned into an opposition politician, was shot dead on Friday night as he was walking in central Moscow.
The murder triggered a wide international reaction, with the world leaders calling for impartial and prompt investigation.
Russian investigators said that murder may have possible links to current events in Ukraine, Nemtsov's business activity and his stance on the Charlie Hebdo attack in Paris.