The arrest of Alparsian Celik at a restaurant in Izmir, on the east coast of Turkey, did not generate much publicity. He is not a well known figure - but he is the man accused of a brutal act of violence in Syria’s civil war which has had widespread international repercussions.

Celik, a Turkish citizen fighting in Syria, led militia fighters who shot dead a Russian pilot after his warplane was shot down by Turkey. The missile strike on the jet led to a bitter confrontation between Moscow and Ankara with a furious Vladimir Putin ordering economic sanctions and rushing advanced weaponry to his forces on the ground.

A tale has unfolded since then of Russians seeking retribution for the death of Lieutenant Colonel Oleg Peshkov, and accusing the Turkish authorities of protecting the pilot’s killer. It has also emerged that a hard-right Turkish nationalist group, the Grey Wolves, one of whose members once attempted to assassinate Pope John Paul II, has become the latest violent addition to Syria’s savage conflict.

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Celik had been freely moving between Syria and Turkey since the shooting down of the plane last November. At the funeral for another Turkish fighter killed in Syria, he explained: “I am here and there, I am going and returning. The martyr was our friend, he was with us in Bayrbucak and the Turkman Mountains.” These two locations are both on Syria’s frontline.

Moscow has demanded that Celik is arrested and extradited and held up the lack of action by the Turkish authorities as a sign of collusion over the killing.There has been persistent reports that the Russian intelligence service FSB, the successor to the KGB, had taken matters into its own hands and was hunting down the wanted man.

The threat of retribution may not be an entirely empty one. The Kremlin has been accused of eliminating enemies in Turkey and elsewhere in the region. On Wednesday two Russians, Yury Anisimov and Alexander Smirnov, were arrested in Istanbul for alleged involvement in the assassination of Abdulvakhid Edelgiryev, a Chechen who had been fighting in Syria. The two men were secret agents, claimed the police, planning further attacks.

Then 32 year old Celik and 13 other Turks who had also been in Syria were suddenly arrested while having dinner at a restaurant in the Hatay district of Izmir.

The arrest could be viewed as an attempt by Turkey’s President Recep Tayyip Erdogan at fence-mending with President Putin. Some officials say, however, that the fighter has been taken into protective custody because of the threat against him by the Russians.

The police in Izmir, meanwhile, claimed that Celik’s arrest had nothing to do with the death of the Russian pilot. Instead, they maintained, he was being investigated for illegally carrying firearms and alleged embezzlement of aid for the Turkmen community in Syria.

But Celik, who is still being held, is being questioned about Lt Col Peshkov’s death. The Independent has learned that he has given a lengthy statement to the office of the General Prosecutor in Izmir outlining his version of what happened.

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Celik now claims that he did not kill the pilot, but rather tried to save him. He said in the deposition “in that very first video, which was disseminated across the social media, at the very moment where the parachute appears, you can hear me giving order not to shoot. And, when the shots rang out, I started to scream. I shouted dozens of times [not to shoot] and to take him prisoner. Those men who were with me at that time were also shouting this same thing. My order was to not to shoot him and to take him prisoner.”

Celik goes on to say that he accepts ultimate responsibility: “But of course, the entire responsibility for the pilot, who was killed by men under my command, lies upon me and I must answer for everything which took place on the Turkman Mountains.”

It is unclear who was giving Celik his orders that day. He and his fellow Turkish nationals say they are fighting in Syria to defend the country’s Turkmen community from the Assad regime. Many of them, however, are members of the Grey Wolves, a paramilitary set up in the late 1960s, which has a long history of association with violence. One of its members, Mehmet Ali Agca, was convicted of the attempted assassination of Pope John Paul II in 1981.

Celik is a member of MHP (Millyetci Hareket Partisi or Nationalist Action Party), the political wing of the Grey Wolves. His father, Ramadan Celik, is a former MHP district mayor who has talked of his pride in his son’s decision to fight in Syria.

The funeral Alparsian Celik attended in Istanbul was of Ibrahim Cucuk, who had held senior positions in the MHP: party members who have been killed at the same Syrian frontline include Burak Misinci, Selani Aymur and several others.

The Grey Wolves have been accused in the past of being part of Turkey’s ‘Deep State’, a secret cabal of the country’s military and the extreme right-wing which conducted a secret war against its opponents: left-wing activists, trade unionists and Kurdish groups.

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The organization is pan-Turkic and its links with the armed forces would not make it natural allies of the ruling AKP party, which has been traditionally opposed to the country’s former military rulers and has put a large number of former senior officers on trial for allegedly planning coups.

Celik, however, belongs to a faction of the MHP which puts more emphasis on Islam, and is said to have forged links with the Islamic government of President Erdogan. Ankara has been backing the Turkmen militias in Syria and projecting them as a counter-weight to Kurdish groups taking over territories being vacated by regime forces and Isis.

In his statements to the prosecutor, Celik adheres to the Turkish government’s narrative that Russian SU-24M fighter had violated Turkish airspace when it was shot down. He said “The plane, having unloaded all its bombs, started to turn around, and was over Turkish airspace at the moment it was shot down. At that moment, when the plane was shot down and we saw the parachute, we were engaged in the process of dragging dead and wounded bodies out from under the ruins.”

Members of the Grey Wolves had taken part in conflicts abroad, including in Chechnya, Azarbaijan, and other parts of former Soviet central Asia. The organisation was also said to be part of Operation Gladio, a campaign of resistance and sabotage organised by Nato and the CIA and to be carried out in the event of a Soviet invasion of the West.

There is no suggestion that Celik was ever involved in Gladio and would, indeed, have been too young to be so. A part of his statement to the prosecutor, however, began “Let them take me to the USSR, let them take me into the Embassy….”

Celik’s lawyer, Murat Ustundag, wanted to stress that “Turkish laws clearly prohibit extradition of a Turkish national to other countries”. The Russian state could, however, request to be a party to any trial of Celik in Turkey, he acknowledged.