New details about the suspect in the New Year’s attack in Istanbul emerged on Wednesday, according to the Turkey’s Anodolu Agency. Officials say they have identified the man, but have not released his name.

Police raided four addresses in the Turkish city of Izmir—about a seven-hour drive west from Konya, where the attacker was thought to have lived in the weeks before the attack—and arrested 11 women and nine men, the state-run news agency reported, citing an anonymous official. Those arrested were reportedly from Dagestan, eastern Turkestan, and Kyrgyzstan.

They also confiscated 41 fake passports from an assortment of countries, 15 fake Turkish identity documents, and a GPS device that police said was used by ISIS militants in conflict areas. Based on photographs, the forged identity documents seem to represent a variety of Central Asian republics, including Uzbekistan and Turkmenistan, as well as Azerbaijan.

Anodolu also reported that police found military and night vision equipment, and an ammunition belt during the raids. Twenty children were detained and put into temporary care.

The Turkish newspaper Hurriyet reports that the suspect had close ties with Turkey’s Uighur community. People from this Turkic ethnic group are found primarily in China, where they number in the millions, but also throughout Central Asian post-Soviet republics and within Turkey itself. A small population of Uighurs lives in Russia.

Hurriyet reports that the attacker arrived in Istanbul on Nov. 20, and went to Konya on Nov. 22 after passing through Ankara. He paid three months’ rent, in cash, for a house, and left Konya several times before the attack on the Reina nightclub in the Ortaköy neighborhood of Istanbul in the early hours of Jan. 1.

After the massacre, the shooter allegedly called an ISIS recruiter named Yusuf Hoca, according to Hurriyet. He also supposedly found his way to a Uighur restaurant and asked employees there to pay his taxi driver.

Some Uighur citizens have been detained as part of the search, the Turkish newspaper also reported, adding that the attacker’s contacts in Konya had fled by the time police located their houses, and that two real estate agents had been detained in relation to the case.

Earlier, Turkish authorities had said that their prime suspect was a Kyrgyz national, who arrived in Turkey with his wife and children weeks before the attack. Turkish media then named a 28-year-old man from the Central Asian republic as the suspect, but he was allowed to fly back to Kyrgystan after being questioned by Turkish agents. The man was in Turkey on business and is no longer a suspect in the attack, officials said.

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Turkey has a fraught terrorism history with ethnic minorities from the republics of the former Soviet Union, particularly the Caucasus. Chechen warlords and their families found refuge there over the course of two grisly wars, the second of which leveled the Chechen capital of Grozny.

A large community of Caucasian refugees and guerrillas has thus been domiciled in Turkey for decades. Partly as a result, since the outbreak of the Syria crisis Turkey has suffered some of the worst “blowback” of any European country from Russian-speaking jihadists.

To date, the bloodiest was the Istanbul Airport gun and bombing attacks in June of last year, the worst act of terrorism in modern Turkish history, in which 45 were killed and over 230 injured. The three assailants, as identified by the Turkish government, were a Russian (reportedly from Dagestan), a Kyrgyz, and an Uzbek, and the ringleader of the operation is said to have been Akhmed Chatayev, a Chechen, whom Russian security forces have named as the “main recruiter of Russians” for ISIS in the North Caucasus.

Nicknamed “Odnorukiy,” or “One-Armed” because he lost the other one, Chatayev’s recruits have so far included Varvara Karaulova, a convert to Islam and a student at the prestigious Moscow State University, who was caught at the Syrian border by the Turkish gendarmerie in 2015 and extradited back to Russia. She was sentenced to 4-and-a-half years for trying to join ISIS.

Chatayev, who is on both the UN and U.S. Treasury Department sanctions lists, was formerly the deputy of Doku Umarov, the now-dead leader of the Caucasus Emirate, a longtime jihadist group that split a few years ago after a contingent pledged allegiance to ISIS. Chatayev was Umarov’s representative in Europe before the latter was killed by Russian forces in 2013.

He’s also been incarcerated in several countries, including Sweden in 2008 (on weapons possession charges), Ukraine in 2009 (at Russia’s request, although he was not extradited), Bulgaria in 2011 (ditto), then again in Georgia in 2012, after a firefight with Georgian special forces in Lopota Gorge. Eleven Islamists were killed in that skirmish, as were three special forces operators.

Yet Chatayev was eventually released in January 2013 because a judge in Tbilisi believed his story, that he was never the leader of the militant band at all but rather an interlocutor sent by the Georgian Interior Ministry to negotiate their surrender to authorities.

He was maimed, Chatayev claimed, as a mere onlooker to a battle he had nothing to do with. And because he had refugee status in Austria, which he obtained a decade earlier as an alleged victim of torture at the hands of Russian authorities, he was allowed to return there upon his release from custody.

As The Daily Beast reported in July, Georgia’s former deputy interior minister did admit to recruiting Chatayev, whom he described as “a good informer and negotiator between us and Islamist underground of the Northern Caucasus; with his help we prevented several terrorist attacks on Georgia.” Gen. Giorgi Lortkipanidze, who recently resigned as the police chief of the Ukrainian port city of Odessa, says that Chatayev turned on his handlers and was arrested while trying to flee Georgia with his Islamist confederates. Lortkipanidze, who commanded the counterterrorism unit that fought the group at Lopota Gorge, also claims that the One-Armed also had his leg amputated after that exchange.

The Chechen’s peregrinations were unknown until June 2015, when a video of him appeared on YouTube. Sitting next to Abu Jihad, a fellow Caucasian from the Republic of Karachai-Cherkessia, Chatayev was now evidently in Syria, heading the Yarmouk Battalion, a Chechen faction of ISIS. He was shown on camera welcoming Dagestani jihadists into the fold and cheering their pledge of allegiance to Abu Bakr al-Baghdadi.

Since the outbreak of the Syria crisis, Turkey has also caught and expelled those it claims are ISIS-affiliated Chechens, including several children. It’s no coincidence that the largest Chechen jihadi site, the Kavkaz Center, is only available in four languages, and one of them is Turkish.

In recent years, however, Ankara has had to push the Chechen issue to the background as it works to improve relations with Moscow, which apparently neither the assassination of the Russian ambassador to Turkey nor a spate of unsolved murders of Russian speakers within Turkey can derail.

A dozen citizens of the ex-Soviet republics and “stans” of Central Asia have been killed in Turkey, most of them with ties to the Chechen conflict. Recent leaked Turkish state evidence indicates that at least three of them, all killed in 2011, were eliminated by five Russian hitmen with possible ties to Moscow Center. Valid Lurakhmaev, a mobbed-up Chechen hitman accused of killing a Chechen ex-militant in Turkey, has been identified by Russian crime reporter Sergei Kanev as working for the FSB, Russia’s domestic intelligence agency, in its anti-terrorism unit in the Caucasus.

In December, the BBC reported that the assassins of Berg-Haj Musaev, Rustam Altemirov and Zaurbek Amriev, three Chechen militants accused of bombing Moscow’s Domodedovo airport that same year, “left a wealth of information in a hired car, including their names and photos, and a USB stick illustrating their lifestyle, from the predictable—fast cars, male friendship and whisky—to the bizarre… a motorbike decorated with Nazi insignia.”

BBC correspondent Murad Batal Shishani pieced together the identity of one of the killers, the owner of the USB stick and rider of the Nazi motorbike, as Nadim Ayupov. He was known in Moscow as a gangster specializing in car theft, Russian organized crime beingfrequently contracted by Russia’s security services who don’t want to get their own hands dirty or who want to maintain an air of plausible deniability to their overseas “wet work.”

In another unsolved murder the BBC investigated, an Uzbek cleric was shot at point-blank range by a man who approached him at the door of a mosque in Istanbul. A former Turkish serviceman told the journalist that an ethnic Uzbek with a Russian passport, who says he was trained by the FSB, was offering $300,000 for each target assassinated.

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With the establishment of ISIS’s “caliphate,” veterans of the Caucasus or Central Asia insurgencies have found a new port of call, and ISIS has even gone so far as to declare a wilayat, or province, on Russian Federation territory, more out of bluster than anything approaching the medieval reality it has been able to impose on now-dwindling areas of Syria and Iraq.

According to Jacob Zenn, a fellow at the Jamestown Foundation, “not including al-Qaeda and also not including Uighurs, if you’re looking at Russian-speaking jihadists, you’re looking at mostly Uzbeks.” And very few of them actually come from Uzbekistan but are rather cultivated as migrant laborers inside Russia. “They get picked up by a jamaat,” he said, referring to the Arabic word for an Islamic council, “with professional ISIS recruiters in Russia who get money for each guy they send to ISIS in Syria. The route is through Turkey. There hasn’t been much done about it.”

The reason for that, Zenn says, is that either Russia has willfully turned a blind eye to the exodus or because the FSB can’t keep track of everyone leaving, particularly from networks in Siberia or the Russian regions away from Moscow.

One of the fiercest battalions in ISIS is actually called the Uzbek Battalion; members from it were reported to have fought in Fallujah and kept the city from falling earlier to pro-Iraqi-government forces last year.

“A large number of the Uzbeks in Syria are actually Kyrgyz citizens. Their motivation is the Kyrgyz nationalist movement in Kyrgyzistan.”

Almost all Tajiks join ISIS as opposed to other Islamist or jihadist factions in Syria, according to Zenn.

As for Russians, the total number fighting with ISIS in Syria and Iraq is impossible to know for sure, as official or semiofficial sources have given varying figures at varying points of time.

Ilya Rogachev, director of the Russian Foreign Ministry's Department on New Challenges and Threats, put the total at “more than 3,200” in November 2016. A year earlier, the FSB estimated that it was closer to 2,900. FSB Director Alexander Bortnikov said in December 2015, that of the 214 jihadists who had repatriated to Russia, “They have all been placed under tight control in law-enforcement agencies: 80 have been tried, 41 more are under arrest.”

Meanwhile, Chechen intelligence, according to the New Yorker, claims that as many as 3,000 to 4,000 Chechens alone have joined ISIS, that is, not counting Russian citizens from other parts of the country.

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Indeed, some believe that Chechen republic leader Ramzan Kadyrov, himself a former Islamist insurgent turned Russian state hireling, saw the rise of ISIS as a convenient opportunity to solve his own domestic terrorism problem by exporting it to the Middle East—an allegation that has already been leveled with increasing evidence against Russia’s security services, writ large.

Elena Milashina, a reporter for Russia’s investigative opposition newspaper Novaya Gazeta, concluded in 2015, based on field research in Dagestan, that “Russian special services have controlled” the flow of jihadists into Syria in the lead-up to the 2014 Sochi Winter Olympics, when the Kremlin feared a terror atrocity would scandalize the international sporting competition it spent so many millions of rubles hosting. “In our village there is a person, a negotiator,” Akhyad Abdullaev, the head of a Dagestani village, told Milashina. “He, together with the FSB, brought several leaders out of the underground and sent them off abroad on jihad.”

The FSB’s so-called “green corridor” for transiting these violent fighters, as The Daily Beast reported, included helping them to obtain passports and other necessaries to migrate to Turkey and/or Georgia, and then ultimately to Syria. The belief was that they’d either be killed on a foreign battlefield and thus become one less headache for law enforcement to worry about, or they’d be picked up upon their return home. One unnamed FSB officer confirmed this policy to the International Crisis Group: “We opened borders, helped them all out and closed the border behind them by criminalizing this type of fighting. If they want to return now, we are waiting for them at the borders.”

A year later, in May 2016, Reuters also, “identified five other Russian radicals who, relatives and local officials say, also left Russia with direct or indirect help from the authorities and ended up in Syria.”

Many Russian-speaking jihadists have gone on to positions of great prominence in the organization.

The most infamous was ISIS’s former “war minister” Abu Omar al-Shishani, a half-Chechen Georgian national and former U.S.-trained special forces operator in the Georgian military who fought against Russia in the 2008 “summer war.”

Shishani was killed in a U.S. airstrike in July 2016. (One of his top confidants was Abu Jihad, Akhmed Chatayev’s YouTube video co-star.)

Shishani’s anointed successor, Colonel Gulmurod Khalimov, is the former head of Tajikistan’s special police force. He was trained by U.S. State Department counterterrorism officials and has threatened to use the skills they taught him against the United States. “Listen, you American pigs. I’ve been three times to America, and I saw how you train fighters to kill Muslims. God willing, I will come with this weapon to your cities, your homes, and we will kill you,” Khalimov said in a propaganda video.

Meanwhile, as The Daily Beast reported last month, Russian President Vladimir Putin’s favorite Chechen, Ramzan Kadyrov—perhaps tacitly acknowledging that it wasn’t enough to ship out jihadists, and may not be possible to nab them when they head home—has sent hit teams to try to track them down in Syria.

If they were on the trail of the Istanbul nightclub killer, they arrived far too late.