Osman Kavala, a prominent business tycoon with a shady background, has been detained in a case related to the multiple coup attempts carried out by the Gülenist Terror Group (FETÖ).

The state-run Anadolu Agency (AA) reported yesterday that Kavala was returning home from a meeting of a Germany-based foundation in Gaziantep when he was detained in Istanbul's Atatürk Airport. AA says that the billionaire businessman, who was a suspect in a case where a U.S. consulate official and two FETÖ members are being investigated, is still being questioned.

Kavala serves in the board of a nonprofit organization. He is known for his close ties to the Democratic People's Party (HDP), a party linked to the PKK terrorist group. The businessman was named the Turkish Soros for his links to the controversial Hungarian-American tycoon and he is well-known for his support of the 2013 Gezi Park riots in Istanbul.

It is not clear whether Kavala funded FETÖ, but 86 defendants, including a textile tycoon and an owner of a popular cafe chain, are currently on trial in Istanbul for running the "business arm" of the terrorist group.

Kavala was detained upon the orders of the Chief Prosecutor's Office in Istanbul, which investigated the two coup attempts in 2013 by infiltrators of FETÖ in the judiciary and law enforcement, and a putsch bid by its infiltrators in the military last summer.

The same probe netted Metin Topuz, a longtime employee of the U.S. Consulate in Istanbul, after prosecutors discovered his intimate ties with dozens of police officers and chiefs associated with FETÖ.

Topuz's detention on Oct.4 sparked a crisis between Turkey and the United States, which responded by suspending visas for Turks. Turkey retaliated with a visa ban for Americans and underlined impartiality of the judiciary in such cases. Another consulate employee was invited to give testimony in the case but refused to do so. Topuz is being charged with espionage and violating constitutional order.

"The suspect had phone contact with 121 people investigated for links to FETÖ and contacted people using ByLock [an encrypted messaging app used solely by the terrorist group] hundreds of times," one section of the indictment reported on by AA claims.

"The suspect acted as a liaison between members of FETÖ and its leader, Fetullah Gülen, who lives in Pennsylvania," the indictment adds, claiming there is strong evidence requiring his arrest.

According to the indictment, the suspect was in contact with a number of former police chiefs in Istanbul where he worked, and all of those police chiefs were involved in the 2013 coup attempts. He was also in touch with Oktay Akkaya, a former lieutenant colonel who was among the main actors in the 2016 coup attempt.

Among his other contacts, Topuz personally met and had phone calls with Zekeriya Öz, a fugitive former prosecutor implicated in a string of FETÖ-linked plots to imprison the group's critics, as well as the 2013 coup attempts. Two days after Kavala's detention, Şaban Kardaş, the head of a think tank, was detained in the same case.

Fugitive suspects in the case include Bayram Andaç and Muharrem Gözüküçük, two FETÖ figures who are accused of plotting a notorious raid on trucks belonging to National Intelligence Organization (MİT) a few years ago.

Investigators had found out that both men had contacts with the U.S. missions. Both men are civilian "imams" for FETÖ according to prosecutors, a term used to describe FETÖ's operatives who commanded the group's members in the military, police, judiciary and bureaucracy.

Andaç organized the controversial raid in southern Turkey that raised outrage and, on Jan. 20, made three phone calls to the U.S. missions in Turkey.

FETÖ, which poses a religious charity, runs a global network of companies and schools. In 2013, its infiltrators tried to topple the government by detaining figures close to the government under the guise of an anti-graft probe. When it failed, the group moved to seize power through its infiltrators in every rank of the army on July 15, 2016. However, this attempt failed as well after the public resisted the bid in an unprecedented move.

A total of 249 people were killed and hundreds were injured in the insurrection attempt. Since then, thousands of people linked to the terrorist group have been arrested or detained, and trials on the coup attempt are still underway.

According to prosecutors, FETÖ increased its clout in Turkey by recruiting unsuspecting followers to its "charity" cause. Multiple investigations revealed that several businesspeople, either through their own will or through extortion, donated large amounts to the group.