Five suspects including a policeman who served in Chechnya have appeared in court over the assassination of Russian opposition leader Boris Nemtsov. Their appearances come a week after the 55-year-old was shot four times in the back while walking along a bridge in full view of the Kremlin with his model girlfriend Anna Duritskaya, 23. One of the suspects - Zaur Dadayev - has allegedly made a statement confirming his guilt, Judge Nataliya Mushnikova said. She did not specify his actions. All of the men were escorted from a bus to Basmanny district court, in Moscow, with their hands bound in front of them and masked men standing either side. Scroll down for video . Five suspects including a policeman who served in Chechnya have appeared in a Moscow court over the assassination of Russian opposition leader Boris Nemtsov. One of the suspects, Tamerlan Eskerkhanov, is pictured above . Another suspect is Zaur Dadayev, who is believed to have served for around ten years in the 'Sever' battalion, part of the interior ministry of Chechnya. Judge Nataliya Mushnikova said he has now made a statement confirming his involvement . Once inside they continued to be flanked by armed guards and were forced to speak from a defendant's cage. The Investigative Committee, the state agency leading the investigation, applied to the court to formally arrest the suspects. All five will now remain in custody. Meanwhile a sixth man thought to be involved in Mr Nemtsov's death blew himself up  after being approached by police at his apartment block, Interfax said. The 30-year-old reportedly threw a grenade at officers in Grozny, Chechnya, on Saturday night before setting one off near himself. The court heard that Dadayev, 33, served for around ten years in the 'Sever' battalion, which is part of the interior ministry of Chechnya. His sister confirmed that he had won medals for bravery and courage. Judge Mushnikova added: 'Dadayev’s involvement in committing this crime is confirmed by, apart from his own confession, the totality of evidence gathered as part of this criminal case.' Anzor Gubashev, who worked for a private security company in Moscow, was named as another suspect. He denied any involvement. Alexander Bortnikov, the head of Russia's federal security service, said Dadayev and Gubashev were 'suspected of carrying out the crime'. It was not clear if either of the men were believed to have fired the shots that killed Mr Nemtsov. Nemtsov (left) and his 23-year-old model girlfriend, Anna Duritskaya (right), were walking through Moscow when he was shot four times in the back . The masked men who escorted the suspects up a set of stairs carried large guns and kept completely covered in dark clothing . Russian state investigators said they are seeking the arrest of five suspects, who appeared in court earlier today . Even when they were inside the building the suspects were kept bent over and well within the grasps of the armed guards . Four guards escort Dadayev, one of the main suspects, to and from the courtroom. They carry several guns between them as well as radios . Dadayev, 33, was forced to speak from inside a defendants' cage during the hearing at the district court . Anzor Gubashev is escorted by a policeman and uses a woolly grey hat to cover his face. State news agencies reported that Gubashev worked for a private security company in Moscow . Three unidentified suspects hide their faces using their jackets and jumpers while waiting behind bars in the courtroom . Aaimani Dadayeva, mother of Dadayev, said she was stunned at the arrest of her son. 'I was informed today that my son has been detained on suspicion of involvement in Boris Nemtsov's murder,' she told Interfax late on Saturday. 'I can't believe it. He could not have committed this crime.' Reports suggest the other suspects include Gubashev's younger brother Shagid and two men - Tamerlan Eskerkhanov and Khamzat Bakhayev. Mr Bortnikov added that the developments had been reported to the president, but he stressed they were continuing 'necessary operative and investigative work' on the case. One suspect, whose face could not be seen, was escorted into the court building by two masked guards who held on to his collar . Another suspect pulled the hood of his grey jacket over his face and had his hands bound in front of him . Russian police guard the yard of Basmanny district court, in Moscow, where the suspects in the killing of Mr Nemtsov were delivered . Russian policemen guard the yard of the court after the suspects arrived via bus and were taken inside . At the time of his death Mr Nemtsov had been working on a report about Russian military involvement in the eastern Ukraine conflict. He was also in the midst of organising a march against the war and had written a number of reports in recent years linking Putin and other politicians to alleged corruption. The shooting occurred a few hours after he had made a radio appearance denouncing Putin for 'mad, aggressive' policies in Ukraine. Surveillance footage apparently showed a man climbing into a white getaway car and being driven away. Russian officials have denied any involvement, with President Vladimir Putin dubbing the murder a 'provocation'. In a speech with officials from the interior ministry, Putin said: 'The most serious attention should be paid to high-profile crimes, including the ones with a political subtext. Russian President Vladimir Putin attends an annual expanded meeting of the Interior Ministry's Board on March 4. He said: 'The most serious attention should be paid to high-profile crimes, including the ones with a political subtext' The body of Mr Nemtsov lies in a body bag in central Moscow in the hours after he was gunned down. He had been organising a march in opposition to the Ukraine conflict at the time of his death . 'Russia should be devoid at last of the kind of shame and tragedies that we have recently endured and seen. 'I mean the murder, the audacious murder of Boris Nemtsov right in the centre of the capital.' He added that he would do all he could to ensure the killers were brought to justice, but has made no comment on the detentions. Russia's top investigative body said it was looking into several possible motives, including that Mr Nemtsov was killed in an attempt to smear Putin's image. It said it was also examining possible connections to Islamic extremism and Mr Nemtsov's personal life. Mourners follow the open-coffin of Mr Nemtsov during a farewell ceremony at the Sakharov centre on Tuesday . Hundreds of floral tributes including bunches of red roses were left on the grave of the murdered Russian opposition leader  after a burial ceremony . A woman weeps as she looks looks towards the coffin of Mr Nemtsov during the farewell ceremony . But Mr Nemtsov's associates said they will only be satisfied if prosecutors track down whoever orchestrated the killing, and not just the people who pulled the trigger. Ilya Yashin, one of Mr Nemtsov's closest allies, said: 'It's extremely important that the matter not be limited to detention of the shooters, whether these are the real killers or not. 'The key task is the identification and detention of who ordered the attack.' Thousands of Russians paid their final respects to Mr Nemtsov when he was laid to rest in the capital earlier this week. The politician's mother Dina, 87, and four children led the mourners with ex-UK prime minister Sir John Major also attending.
Investigative Committee applied to court for formal arrest of five suspects accused of Boris Nemtsov's murder . Appearances come a week after 55-year-old was shot four times in the back while walking near the Kremlin . Suspect Zaur Dadayev has now admitted involvement in the crime, according to Russian news authorities . He was arrested in Ingushetia and is thought to have served for ten years in the 'Sever' battalion in Chechnya . All of the men were escorted into court from a bus with hands bound and masked guards either side . Other suspects are Anzor Gubashev, Shagid Gubashev, Khamzat Bakhayev and Tamerlan Eskerkhanov . Meanwhile a sixth man thought to be involved blew himself up with a grenade after being approached by police .