Three others held over killing of opposition politician ReutersPeople hold Ukrainian and Russian national flags during a march in central Moscow on March 1 to commemorate slain Kremlin critic Boris Nemtsov.Russian investigators Sunday formally charged two men from the restive Caucasus region with the murder last month of opposition politician Boris Nemtsov, and said three more suspects had been arrested in the case. The string of arrests, which began Saturday, was a dramatic turn in the high-profile case, in which Western leaders have called on the Kremlin to conduct a transparent and complete probe. Officials on Sunday gave no indication of the possible motive for the killing and few details on the five suspects. All five were suspected of murder committed by a group for commercial gain, usually used in contract killings, the Interfax news agency reported. Read an expanded version of this report at WSJ.com