MOSCOW (AP) — Russia's top investigative body said Saturday it is looking into several possible motives for the killing of prominent opposition figure Boris Nemtsov, including an attempt to destabilize the state, Islamic extremism, the Ukraine conflict and his personal life. 
 
 A Russian family walk to lay flowers at the place where Boris Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down, at Red Square in Moscow, Russia,... (Associated Press) 
 
 People lays flowers at the place where Boris Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was attacked, at Red Square in Moscow, Russia, Saturday, Feb.... (Associated Press) 
 
 FILE - In this Nov. 22, 2004 file photo, Boris Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, right, listens to Petro Poroshenko while Yulia Tymoshenko,... (Associated Press) 
 
 Flowers lie on the ground as Russian police officers stand near the place where Boris Nemtsov, a former Russian deputy prime minister and opposition leader, was kiiled at Red Square with the Kremlin Wall... (Associated Press) 
 
 Russian police officers stand next to traces of the body of Boris Nemtsov, a former Russian deputy prime minister and opposition leader, at Red Square with the Kremlin Wall in the background in Moscow,... (Associated Press) 
 
 Russian opposition leader Ilya Yashin, center, reacts as police investigate the the body of Boris Nemtsov, a former Russian deputy prime minister and opposition leader at Red Square in Moscow, Russia,... (Associated Press) 
 
 Russian police investigate the the body of Boris Nemtsov, a former Russian deputy prime minister and opposition leader at Red Square with St. Basil Cathidral in the background in Moscow, Russia, Saturday,... (Associated Press) 
 
 Police and medics surround the body of Boris Nemtsov, a leading opposition figure and former deputy prime minister, who was shot and killed near the Kremlin, Moscow in the early hours of Saturday, Feb.... (Associated Press) 
 
 FILE - In this file photo taken on Saturday, March 15, 2014, Boris Nemtsov, a former Russian deputy prime minister and opposition leader addresses demonstrators during a massive rally to oppose president... (Associated Press) 
 
 Police and medics surround the body of Boris Nemtsov, a leading opposition figure and former deputy prime minister, who was shot and killed near the Kremlin, Moscow in the early hours of Saturday, Feb.... (Associated Press) 
 
 FILE - In this file photo taken on Thursday, May 30, 2013, Boris Nemtsov, a former Russian deputy prime minister and opposition leader, presents a report claiming widespread corruption during preparations... (Associated Press) 
 
 A man reacts as he lays flowers at the place where Boris Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down, at Red Square in Moscow, Russia,... (Associated Press) 
 
 FILE - In this file photo taken on Sunday, May 6, 2012, Opposition leader Boris Nemtsov uses a loud speaker during an opposition rally in downtown Moscow, Russia. Russia's Interior Ministry says Boris... (Associated Press) 
 
 A municipal worker washes the place where Boris Nemtsov, a former Russian deputy prime minister and opposition leader, was kiiled at Red Square with St. Basil Cathidral in the background in Moscow, Russia,... (Associated Press) 
 
 People react as they lay flowers at the place where Boris Nemtsov, a charismatic Russian opposition leader and sharp critic of President Vladimir Putin, was gunned down, at Red Square in Moscow, Saturday,... (Associated Press) 
 
 A statement from the body, the Investigative Committee, didn't address the possibility seen as likely by many of Nemtsov's supporters — that he was killed for being one of President Vladimir Putin's most adamant and visible critics. 
 
 The 55-year-old Nemtsov was gunned down Friday near midnight as he walked on a bridge near the Kremlin with a female companion. The killing came just a few hours after a radio interview in which he denounced Putin's "mad, aggressive" policies and the day before he was to help lead a rally protesting Russia's actions in the Ukraine crisis and the economic crisis at home. 
 
 After his death, organizers canceled the rally and instead called for a demonstration to mourn him on Sunday in central Moscow. The city gave quick approval for that gathering, in contrast to its usual slow and grudging permission for opposition rallies. 
 
 The Investigative Committee said it was looking into whether Nemtsov had been killed as a "sacrificial victim for those who do not shun any method for achieving their political goals," a suggestion echoing the comments by Putin's spokesman and other Russian politicians that the attack was a "provocation" against the state. 
 
 It also said it was considering whether there was "personal enmity" toward him in his domestic life. State-controlled TV and Kremlin-friendly media outlets on Saturday gave considerable attention to Nemtsov's companion, identifying her as a Ukrainian model 30 years his junior and showing photos of her in alluring poses. The Investigative Committee said the pair were headed for Nemtsov's apartment. 
 
 The statement also said it was investigating whether the killing was connected to the Ukraine conflict, where Russia-backed separatists have been fighting Ukrainian forces since last April, or whether there was a connection to Islamic extremism. 
 
 Nemtsov had been one of Putin's most visible critics and his death hit other members of the opposition hard. The mourning march on Sunday could serve to galvanize the beleaguered and marginalized opposition, or it could prove to be a brief catharsis after which emotions dissipate. 
 
 Through the morning, hundreds of people came to the site of Nemtsov's death to lay flowers. 
 
 Nemtsov was working on a report presenting evidence that he believed proved Russia's direct involvement in the separatist rebellion that has raged in eastern Ukraine since April. Moscow denies backing the rebels with troops and sophisticated weapons. 
 
 Putin ordered Russia's top law enforcement chiefs to personally oversee the investigation of Nemtsov's killing. 
 
 "Putin noted that this cruel murder has all the makings of a contract hit and is extremely provocative," presidential spokesman Dmitry Peskov said in remarks carried by Russian news agencies. 
 
 Ramzan Kadyrov, the Putin-backed leader of Chechnya, raised the suggestion into an accusation. 
 
 "There's no doubt that Nemtsov's killing was organized by Western special services, trying by any means to create internal conflict in Russia," he said on Instagram. 
 
 President Barack Obama said the Russian people "lost one of the most dedicated and eloquent defenders of their rights." 
 
 German Chancellor Angela Merkel praised Nemtsov's courage in criticizing Kremlin policies, and urged Putin to insure that the killers are brought to justice, her spokesman Steffen Seibert said. 
 
 Former Soviet leader Mikhail Gorbachev echoed the suggestion that the killing was a provocation. "It's an attempt to push the situation into complications, maybe even to destabilizing the situation in the country," he was quoted as saying by the Interfax news agency. 
 
 Communist Party leader Gennady Zyuganov agreed. "It's a provocation; for big fires, sacrificial figures are necessary," Interfax quoted him as saying. 
 
 Nemtsov frequently assailed the government's inefficiency, rampant corruption and Ukraine policy. 
 
 In an interview with the Sobesednik newspaper, Nemtsov said earlier this month that his 86-year old mother was afraid that Putin could have him killed. Asked if he had such fears himself, he responded: "If I were afraid I wouldn't have led an opposition party." 
 
 Speaking on radio just a few hours before his death, he accused Putin of plunging Russia into crisis by his "mad, aggressive and deadly policy of war against Ukraine." 
 
 Kasyanov, the former prime minister, said he was shocked. 
 
 "In the 21st century, a leader of the opposition is being demonstratively shot just outside the walls of the Kremlin!". 
 
 "This is a monstrous tragedy and a loss for us all," Alexei Navalny, Russia's most prominent opposition figure, said on his Facebook page. He is currently on a 15-day jail sentence for handing out leaflets without authorization. 
 
 "The country is rolling into the abyss," Kasyanov, the former prime minister, told reporters as Nemtsov's body, placed in a plastic bag, was removed on a rainy and cold night, as the Kremlin bells chimed nearby. 
 
 Nemtsov served as a regional governor and then a deputy prime minister in the 1990s and once was seen as a possible successor to Boris Yeltsin, Russia's first elected president. 
 
 Nemtsov was widely liked for his good humor, larger-than-life character and quick wit, but he and other top opposition figures long have been purged from state television and steadily marginalized by the Kremlin. 
 
 ___ 
 
 Associated Press writers Vladimir Isachenkov and Laura Mills in Moscow and Jake Pearson in New York contributed to this report. ||||| “I love Russia and want the best for her, so for me criticizing Putin is a very patriotic activity because these people are leading Russia to ruin,” Mr. Nemtsov said in an interview in 2011, republished Saturday on the Meduza news site. “Everybody who supports them in fact supports a regime that is destroying the country, and so they are the ones who hate Russia. And those who criticize this regime, those who fight against it, they are the patriots.” 
 
 In recent years, Mr. Nemtsov’s star had been eclipsed by Aleksei A. Navalny, the anticorruption blogger who played a leading role in the 2011 protests. But Mr. Nemtsov remained active and was a leading organizer of this weekend’s planned rally. 
 
 Mr. Nemtsov was organizing the rally in part because Mr. Navalny is currently serving a two-week jail sentence for handing out leaflets on the subway. The rally was also noteworthy because it was the first political action inside Russia specifically endorsed by Mikhail B. Khodorkovsky, the exiled former political prisoner, who had signed the petition for a parade permit. 
 
 The investigative committee of the prosecutor’s office said gunmen shot Mr. Nemtsov four times in the back as he walked over the bridge, and by accident or design theatrically placed his body on the wet asphalt with the Kremlin visible behind. No suspects have been reported to be in custody. 
 
 While such contract street killings were commonplace in Moscow in the 1990s, the violence had dwindled under Mr. Putin, making the killing of Mr. Nemtsov all the more shocking. He is by far the most prominent public figure to die in such a fashion, though just one in a string of murders of opponents of Mr. Putin, most notoriously the journalist Anna Politkovskaya, the human rights researcher Natalia Estemirova and the security service defector Aleksandr V. Litvinenko. And while low-level criminals have been detained in some cases, the investigations in Russia never traced back to those who ordered the murders. 
 
 The Interfax news agency cited an unnamed security service operative as saying the murder was a “provocation,” coming as it did just days before the opposition march. ||||| Ukraine's President Petro Poroshenko addresses the commemoration for people from the so-called ''Heavenly Sotnya'' (Hundred), who were killed in anti-government protests in 2014, at Independence Square in Kiev February 20, 2015. 
 
 (This refiled version of the story corrects spelling error in second paragraph) 
 
 KIEV (Reuters) - Ukrainian President Petro Poroshenko said on Saturday Russian opposition politician Boris Nemtsov was murdered because he planned to disclose evidence of Russia's involvement in Ukraine's separatist conflict. 
 
 Poroshenko paid tribute to Nemtsov, who was shot dead late on Friday, and said the fierce critic of President Vladimir Putin had told him a couple of weeks ago that he had proof of Russia's role in the Ukraine crisis and would reveal it. 
 
 "He said he would reveal persuasive evidence of the involvement of Russian armed forces in Ukraine. Someone was very afraid of this ... They killed him," Poroshenko said in televised comments during a visit to the city of Vinnytsia. 
 
 More than 5,600 people have been killed since pro-Russian separatists rebelled in east Ukraine last April, after the ousting of a Moscow-backed president in Kiev and Russia's annexation of the Crimea peninsula. 
 
 Kiev and its Western allies say the rebels are funded and armed by Moscow, and backed by Russian military units. Moscow denies aiding sympathisers in Ukraine, and says heavily armed Russian-speaking troops operating without insignia there are not its men. 
 
 (Reporting by Alessandra Prentice and Polina Devitt,; Additional reporting by Margarita Chornokondratenko,; Editing by Alexander Winning and Timothy Heritage)
– Russian investigators promise to find the gunmen who murdered Boris Nemtsov within sight of the Kremlin, and the president of Ukraine thinks they won't have far to look. Petro Poroshenko says Nemtsov was poised to release evidence proving that Russia was playing a big role in the Ukraine conflict despite Vladimir Putin's assertions to the contrary, reports Reuters. "He said he would reveal persuasive evidence of the involvement of Russian armed forces in Ukraine," says Poroshenko. "Someone was very afraid of this. ... They killed him." Russian investigators, meanwhile, said they were looking at a range of motives, including the idea that enemies of Putin killed Nemtsov "as a provocation to destabilize the political situation in the country," reports the New York Times. They also made a point to say they would look into his personal life, and state TV emphasized that the 55-year-old was walking with a much younger model when he was shot to death, reports AP. Putin himself sent a message to Nemtsov's mother promising that "everything will be done so that the organizers and perpetrators of a vile and cynical murder get the punishment they deserve.” It did not mention that in a recent interview, Nemtsov talked about how his mother was "truly scared" that Putin would have him killed because of his unrelenting criticism of the Kremlin. Nemtsov supporters plan a march in Moscow tomorrow.