Moscow, May 18 (IANS): The Duma, the lower house of the Russian Parliament, has refused to open a parliamentary investigation into the assassination of former deputy prime minister and Russian opposition leader Boris Nemtsov, who was murdered on February 27, parliamentarian Dmitry Gudkov said on Monday.

Gudkov, the lawmaker who originally requested the parliamentary commission to investigate Nemstov's murder, said that the Constitutional Legislation Committee of the Duma rejected his request on the grounds that "the investigation of crimes is a matter of the investigating bodies", Efe news agency reported.

The refusal was further justified in that "the subject of a parliamentary inquiry shall not be establishing the guilt of certain persons in a crime".

According to the deputy, this is simply a veiled way of saying "you will know the truth that we allow you to know".

Gudkov agreed that only judges can establish guilt in a crime, but underlined that the parliamentary inquiry was an "element of control" that allows society to verify the performance and transparency of investigating bodies.

Meanwhile, five Chechens have been arrested and charged by the Russian court for the crime.

The main suspect, Zaur Dadaev, admitted his guilt during initial questioning, but later retracted his statement, arguing that the police had wrested the confession by force.

Shortly before he was killed, Nemtsov had collected dozens of testimonies about Russia's direct involvement in the Ukraine conflict one year ago, when Crimea acceded to Russsia and pro-Russian factions in the east of the country revolted.

Nemtsov's investigations were the basis for the report, "Putin: War", presented last week by the late opposition leader's colleagues, claiming that Russian soldiers were in fact deployed in eastern Ukraine, and that hundreds died in combat.