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Family members of the Turkish gunman who shot dead Russian ambassador Andrei Karlov have been released from police questioning.
A number of relatives of Mevlut Mert Altintas were taken into custody earlier this week as police attempted to establish the background to the shooting.
Karlov, the ambassador to Turkey, was shot in the back by Altintas, himself a member of security, as the Russian was giving a speech on Monday.
Altintas' family were released by police on Thursday, according to CNN.
- Video report by ITV News Senior International Correspondent John Irvine
The body of Andrei Karlov, the Russian ambassador to Turkey who was gunned down by a Turkish policeman, was returned to his home today.
His widow and mother broke down in tears over his coffin, draped in a Russian flag, when it arrived at the Vnukovo International Airport in Moscow.
It came after the announcement that the street of the Russian Embassy in Turkey will be renamed after Karlov.
The Turkish policeman who assassinated Russia's ambassador was unlikely to have acted alone, a senior Turkish government official said.
The "well-planned" killing was "fully professional, not a one-man action", the official, who spoke on condition of anonymity, added.
Turkish authorities have not publicly released any information on the policeman's possible motive.
Turkey and Russia, which have backed opposing sides in the Syrian war, vowed not to let the killing disrupt conciliation efforts.
The body of the Russian ambassador who was assassinated by a Turkish policeman was flown home today.
Andrei Karlov, who was gunned down in an art gallery on Monday, was carried across Esenboga airport's tarmac in a coffin draped in the Russian flag.
A ceremony attended by Ankara's top diplomats and Turkey's Deputy Prime Minister Tugrul Turkes was held before his departure.
Karlov's wife Marina stood in the front row, holding two red carnations. She wept as her husband's coffin was carried by a Turkish guard of honour.
Russian investigators have arrived in Ankara after the assassination of Russia's ambassador to Turkey Andrey Karlov.
They are working to determine whether Mevlut Mert Altintas was working as a "lone gunman" or part of a "wider conspiracy".
The assassination of the Russian ambassador to Turkey will not hinder the Syria peace deal, the Kremlin said.
Russian President Vladimir Putin has ordered intelligence services to step up security for Russian embassies abroad.
But at the moment there are no plans to evacuate Russian diplomats from Turkey.
A group of Russian investigators have already arrived in Ankara, the Kremlin added.
Turkish police have detained a man who fired shots outside the US embassy in Ankara just hours after the Russian ambassador to Turkey was assassinated.
The man took out a pump action shotgun he hid in his coat and fired around eight shots in the air, police said.
No one was hurt as the embassy's security guards overpowered the gunman.
The US embassy is located just across the street from the art gallery where Russian ambassador Andrey Karlov was shot and killed as he gave a speech on Monday night.
Turkish policeman Mevlut Mert Altintas, who was later shot and killed by police, has been named as the gunman.
Altinas is said to have shouted "don't forget Aleppo" during the attack, appearing to condemn Russia's military role in Syria.
The United Nations Security Council has condemned "in the strongest terms" the assassination of Russia's ambassador to Turkey Andrey Karlov.
A statement from the council on Monday said that "any acts of terrorism are criminal and unjustifiable, regardless of their motivation, wherever, whenever and by whomsoever committed".
The council also expressed its "deep condolences" to Karlov's family and the Russian government.
The murder of Russian diplomat Andrey Karlov will not bring the Syrian civil war any closer to an end, Defence Secretary Sir Michael Fallon said.
Sir Michael told MPs the shooting was a "shocking act involving a diplomat who should otherwise, of course, enjoy proper protection".
He added: "His murder does not bring any conflict in the Middle East further to a resolution."
The gunman who shot Karlov was heard to shout "Don't forget Aleppo! Don't Forget Syria".
Latest ITV News reports
"It was like a movie", says Burhan Ozbilici, who captured the moment Mevlut Mert Altintas shot and killed Andrey Karlov.
Andrey Karlov has been killed in a gun attack at a photo exhibition in the Turkish capital Ankara.