( CNN ) A sixth suspect in the shooting death of a top Russian opposition figure blew himself up after a standoff with police in the capital of the Chechen Republic , state-run television reported Sunday . Beslan Shavanov , 30 , was holed up in a building in Grozny when police arrived to arrest him Saturday afternoon , Russia 24 reported . Police surrounded the building and Shavano tried to escape , throwing a grenade at police officers before blowing himself up , the station said . The news came as Russian authorities reported making five other arrests in connection with Boris Nemtsov 's killing . One of those arrested claims to have an alibi , according to Russia 's Sputnik News . `` At the time of the murder , I was at work as I usually am every day . There are many people , my colleagues , who will confirm this , '' the news agency quoted Tamerlan Eskerkhanov as saying in Moscow 's Basmanny District Court . Two of the suspects have been formally charged and three `` remain under the status of suspects , '' court spokeswoman Anna Fadeyeva told Sputnik . Nemtsov , one of President Vladimir Putin 's most outspoken critics , was shot in the back on a Moscow bridge as he walked with his girlfriend near the Kremlin in late February . Surveillance video showed someone darting from the sidewalk and into a nearby car right after Nemtsov collapsed . Putin has been informed of the arrests in connection with Nemtsov 's death , Russian media said , citing Federal Security Service director Alexander Bortnikov . Two of the other suspects are Anzor Gubashev and Zaur Dadayev , Bortnikov said in a televised statement . The others are Ramzan Bakhayev and Shagit Gubashev , Anzor 's younger brother , according to a Sputnik report that also said Dadayev was the only one of the five to plead guilty -- though to what crimes was not clear . Bortnikov said those detained are from the southern region of the North Caucasus , which for years has been a hotbed of unrest and rebellion against Moscow . Dadayev had previously served as an officer in a Chechen police battalion , Albert Barakhayev , secretary of the Security Council of the Caucasian republic of Ingushetia , told the official news agency TASS . Dadayev was the deputy commander of one of the Chechen Republic 's Ministry of Internal Affairs groups , Sputnik reported , adding that Gubashev worked at a security firm in Moscow . Gubashev was arrested between the town of Malgobek and the village of Voznesenovskaya , while Dadayev was arrested in the city of Magas , Barakhayev told TASS . The slain opposition leader 's daughter , Zhanna Nemtsova , told CNN she is `` not surprised both of them ( are ) of Caucasus origin . It was predictable . '' Nemtsova said the only things she knew about the arrests came from media reports , as authorities did not contact her immediately . Later Saturday , a southern Russian law enforcement official told state news agency RIA Novosti that two more men were arrested . The two suspects in the second arrest were not named , but one of them was driving with Dadayev , and the other man is Gubashev 's younger brother , Barakhayev said . Like Gubashev and Dadayev , those two suspects are also ethnic Chechens , according to Barakhayev . After Nemtsov 's shooting Putin blamed extremists and protesters who he said were trying to stir internal strife in Russia . Many opposition sympathizers and people close to Nemtsov have pointed the finger at Putin and the Russian government he leads . They note that Nemtsov -- the deputy prime minister under former President Boris Yeltsin -- is the latest in a list of Putin 's opponents who have been killed or imprisoned . Nemtsov had also been arrested several times for speaking against the government . In her first TV interview since her father 's death , Nemtsova told CNN that Putin shares `` political responsibility '' for her father 's assassination . She spoke from Germany . `` I do n't believe in the official investigation , '' she said Saturday . Other opposition figures previously jailed or killed include Anna Politkovskaya , a journalist critical of Russia 's war in Chechnya . She was gunned down at the entrance to her Moscow apartment in 2006 . There was also business magnate Mikhail Khodorkovsky , who backed an opposition party and accused Putin of corruption . Khodorkovsky landed in jail after a conviction on tax fraud , which he said was a ploy to take away his oil company . The government rejected the claim . Putin pardoned him in 2013 . Former Russian security agent Alexander Litvinenko was poisoned by a lethal dose of radioactive polonium , his tea spiked in a London hotel during a meeting with two former Russian security service men in 2006 . He had blamed the agency for orchestrating a series of apartment bombings in Russia in 1999 that left hundreds dead and led to Russia 's invasion of Chechnya later that year . The Kremlin has staunchly denied accusations that it or its agents are targeting political opponents or had anything to do with the deaths . CNN 's Catherine Shoichet , Ben Brumfield , Elena Sandyrev , Brian Walker , Greg Botelho , Joshua Berlinger and Alla Eshchenko contributed to this report .
With police surrounding hiding place , first suspect kills himself , Russian media say . One of the men arrested reportedly served as an officer in a Chechen police battalion . Four of the five suspects are ethnic Chechens , law enforcement official tells media .