MOSCOW - Russian investigators are expected to indict five men with the murder of opposition leader Boris Nemtsov, a brazen killing which sent shockwaves among the opposition earlier this year.

Nemtsov, a top opponent of Russian President Vladimir Putin, was shot late at night on Feb. 27 as he was walking just outside the Kremlin. Five Chechen men have been arrested on charges of involvement in the killing, but it has remained unclear who ordered the attack.

The Investigative Committee, Russia's top investigative body, said in a statement that investigators would file the final indictment against the five men later on Tuesday. The committee said they are expecting the probe to wrap up in January.

The key suspect in Nemtsov's killing was a senior officer in the security forces of Chechen leader Ramzan Kadyrov while the organizer named by the investigators was a personal driver of senior commander and Kadyrov ally Ruslan Geremeyev.

Nemtsov's family has been petitioning investigators to look into Kadyrov's possible involvement in the murder as well as question Geremeyev who is believed to have fled Chechnya.

Vadim Prokhorov, lawyer for Nemtsov's family, told the Interfax news agency on Tuesday that Geremeyev's driver has been singled out as a scapegoat "in order to deflect the attention from Kadyrov's inner circle."