As rumors circulated that Germany took a step on Friday to capture Adil Öksüz, one of Turkey's most wanted men, German officials told state-run Anadolu Agency (AA) that they were investigating claims that he was seen in the European country.

Öksüz, a theology lecturer by profession, is accused of masterminding the July 15, 2016 coup attempt by the Gülenist Terror Group (FETÖ) in which he served as a point man for its leader, Fetullah Gülen. After his controversial release from custody one day after his capture, he remains at large.

Several Turkish media outlets claimed on Friday that German Chancellor Angela Merkel told President Recep Tayyip Erdoğan during a phone call on Thursday evening that Berlin issued a search warrant for Öksüz.

A senior German official, who spoke on condition of anonymity, told AA that after a Turkish diplomatic initiative last month, the authorities investigated claims that Öksüz was seen in a number of different cities in Germany.

"So far, we have no indications that support the claim that Adil Öksüz might be in Germany. But our authorities continue to investigate these claims," the official said, adding that the Federal Criminal Police Office (BKA) was taking steps on this issue.

Turkish diplomatic sources speaking to AA also confirmed that Germany has responded to Turkey's diplomatic note and informed Ankara about the outcome of their inquiries so far.

During a regular news conference on Friday, German Interior Ministry spokesman Johannes Dimroth declined to make a comment on the arrest warrant.

Turkey's government delivered several diplomatic notes to the German state in the last couple of months and asked whether claims made in various Turkish newspapers were true.

Ankara demanded that German authorities investigate the claims, and if these are proven to be true, take the necessary measures to arrest Öksüz and send him to Turkey for trial. Öksüz faces a life sentence for his role in the putsch bid.

On Nov.21, a court in capital Ankara formally drafted a request for the extradition of Öksüz from Germany.

Öksüz was captured at Akıncı military base in the capital that served as the command center of the putschists, after the coup was quelled, but a court controversially released him from custody one day later. Öksüz was last spotted in his hometown of Sakarya before he disappeared.

The Fourth High Criminal Court tasked with the trial of 486 defendants, including Öksüz, for the takeover of Akıncı Air Base, asked the Justice Ministry to convey such requests to their foreign counterparts, AA has reported.

EU Affairs Minister Ömer Çelik said in August when sightings of Öksüz in the German cities of Frankfurt and Ulm were first reported that it was "a crystal clear matter" for both countries and that they expected Berlin to act in line with "our cooperation." "No friend of Turkey can shelter a killer. It would be worrying that someone wanted by Turkish security forces for their involvement in the killing of people would be housed by a friend," Çelik said, pointing to remarks from a German government spokesman who said they cannot confirm or deny if Öksüz was in Germany.

Ankara has placed Öksüz in the red category of the country's most wanted terrorism suspects, offering a reward of up to TL 4 million ($1.1 million) for tips leading to his capture. Referred to as the "black box" of FETÖ, Öksüz reportedly acted as the Air Force leader for the terrorist group, which is known for its widespread infiltration of the military.

Gülen and Öksüz are being tried in absentia in coup cases that saw the detention and arrests of hundreds of military officers linked to FETÖ. Both men face multiple life sentences for their suspected role in the coup attempt that came three years after FETÖ members in the judiciary and law enforcement tried two other unsuccessful coup attempts.

Since last year's coup attempt, Ankara has worked tirelessly to locate FETÖ members worldwide, focusing on its commercial entities. European countries, which have also been accused of harboring supporters of other terrorist groups, have not responded to Ankara's extradition demands, unlike Arab and Asian countries that have carried out most of Ankara's demands.

Ankara singles out Germany among European countries for embracing some 250 fugitive diplomats and soldiers accused of involvement in the coup with suspected links to FETÖ. A report, "The FETÖ Settlement in Germany and Germany's FETÖ Policy," says that FETÖ has been using Germany as its main functioning center and that German authorities have embraced the structures of the group with open arms.

Unconfirmed reports say that about 4,000 FETÖ suspects left for Germany after the coup attempt, while several suspects, including former military officers and diplomats accused of involvement in the coup attempt, applied for asylum. Turkish leaders frequently criticize Berlin for allowing activities of terrorist groups, including the PKK and FETÖ.

FETÖ, which runs a global network of companies and schools, operates dozens of private schools, media outlets and companies in Germany as well.