( CNN ) Russian police moved with surprising speed to arrest five suspects , all of them Chechens , in the killing of opposition figure Boris Nemtsov . They tried to arrest a sixth suspect , but he reportedly threw a grenade at the arresting officers and then blew himself up . Yet that speed has only raised more questions about who wanted Nemtsov dead -- and why ? Conspiracy theories are rife , but so far , none seem totally convincing . • The Kremlin did it . Some members of Russia 's opposition -- and Nemtsov 's daughter -- are convinced Russia 's government was behind Nemtsov 's killing . But why ? And why now ? Nemtsov , 55 , had been an opposition leader for years and had recently been overshadowed by younger members of the opposition such as Alexey Navalny . So killing him now does n't seem to make sense . Some of Nemtsov 's supporters claim he had become a bigger threat to the Kremlin , pointing to information he was allegedly uncovering on Russia 's military role in Ukraine that could undermine the Kremlin 's claims that its forces fighting in Ukraine have been just `` volunteers . '' But the dramatic staging of the killing -- he was shot in the back on a famous Moscow bridge against the backdrop of Red Square and the Kremlin , where Putin has his office -- seems a bit too obvious . And how exactly does it help Putin to look like a killer ? • The West did it . Some Russian politicians and media personalities close to the Kremlin charge that Putin 's foes in the West orchestrated the killing to damage the Russian President 's image and ignite a civil war in Russia . But why would Washington want to destroy someone who was championing democracy and who is friendly to the United States ? ( Conspiracy theorists reply : to create a `` sacrificial lamb '' and blame the slaughter on Putin . ) • It was the Chechens . Here , the plot thickens . The key suspect , Zaur Dadayev , reportedly initially confessed to being involved with the shooting . But then , Russian media reported , he denied involvement . Russian officials have alleged that Dadayev , a former security officer and fervent Muslim , decided to punish Nemtsov for supporting the rights of the French Charlie Hebdo journalists to publish cartoons of the Prophet Mohammed . But Nemtsov 's allies point out that he was not anti-Muslim and rarely spoke of the cartoons -- he was by no means a central figure in the cartoon story . To make things more complicated , the strongman leader of Chechnya , Ramzan Kadyrov , praised Dadayev as a brave soldier , a religious man and a `` real patriot . '' But on Tuesday , Putin awarded Kadyrov the Order of Honor , and the Chechen leader pledged he would die for Putin . A further twist is that Chechens reportedly are fighting in Ukraine -- on both sides of the battle line ( for the Ukrainian government and for the Russian-allied separatists . ) That 's led some back to the theory that Nemtsov was killed because of his allegedly explosive information on Russia 's role in Ukraine . • The Ukrainians did it . Many Russians are convinced that what they call the `` fascist '' Kiev government would stop at nothing to frame Putin . After all , a significant number of people , fed by domestic propaganda , still believe the Ukrainian air force shot down Malaysian Airlines Flight 17 over Ukraine despite much of the evidence pointing to Russian-backed rebels as the culprits . • It was domestic extremists . Supporters of this theory are mainly in the opposition camp . They accuse the Kremlin of whipping up hatred against the so-called Fifth Column -- `` traitors '' who are trying to undermine Russia from within . Photos of opposition leaders labeled `` traitors '' have been posted in Russian cities , while at an anti-Ukraine rally in Moscow just days before Nemtsov 's assassination , Russians loyal to Putin carried signs and placards with pictures of those `` traitors , '' including Nemtsov . But whatever the reality of what happened in Moscow , high-profile killings in Russia , especially ones with a political connection , are rarely solved . Chechens were convicted of killing journalist Anna Politkovskaya , for example , but there still is no explanation of why they did it or who organized the murder . Now , with Nemtsov 's killing , Russian officials and Kremlin-friendly media have whipped up a sandstorm of theories , confounding the most intrepid attempts at establishing the truth . Will things play out any differently this time ?
Russian opposition leader Jill Dougherty was killed last month . Boris Nemtsov : Conspiracy theories about the killing are rife , but none seem convincing .