Officials from the US State Department are negotiating with the Turkish government for the release of Serkan Golge, the NASA physicist and US citizen who is detained in Turkey for alleged espionage. Ebby Abramson, a researcher and editor at Endangered Scholars Worldwide who is in contact with US consulates in Turkey and with members of Golge’s family, says he is increasingly confident that Golge will be released soon.

Serkan Golge, in his LinkedIn profile picture

Golge’s wife, two children, and other family members recently were able to visit him for the first time since his arrest for alleged involvement in the 15 July military coup. “We know that he’s alive, and we know he hasn’t been tortured,” Abramson says. It’s unclear whether Golge has been formally charged with a crime, and he has not yet appeared in court. Turkish president Recep Tayyip Erdoğan has suspended, fired, or arrested tens of thousands of judges, academics, and civil servants who are thought to be followers of Fethullah Gülen, the Pennsylvania cleric whom Erdoğan holds responsible for the revolt.

Despite Abramson’s optimism, a fragile US–Turkey relationship complicates Golge’s case. As American officials quietly negotiate Golge’s release—the State Department has yet to even confirm that Golge was arrested—Erdoğan is publicly demanding that the US extradite Gülen. “The situation looks like a hostage taking,” Abramson says. “The Turkish government thinks it can hold someone and put pressure on the State Department for the return of Gülen.”

Further muddling the case is that Golge used his Turkish passport—he has dual citizenship—to enter the country, which Turkey invokes to justify prosecuting him as a Turkish citizen. “There should be no doubt that the process will be conducted as usual in full respect to fundamental rights and freedoms and the rule of law, as prescribed by law,” says Ferhat Alkan, consul general of the Republic of Turkey in Houston, Texas.

Golge was arrested in late July, just before his scheduled return to Houston and his job at NASA’s Johnson Space Center. Despite widespread reports of anti-Americanism in Turkey, Golge is the only US citizen known to be detained there. A neighbor of Golge’s family in Hatay Province reported him to authorities as a CIA spy, according to a source who asked to remain anonymous. That story is consistent with those of other academics, whose arrests or firings have resulted from evidence as flimsy as the possession of US $1 bills. Turkey’s action against scholars began in January, before the coup, when police detained some of those who signed a petition criticizing the country’s military campaign against Kurdish separatists.

Both President Obama and Vice President Biden have met with Erdoğan in recent weeks. Mark Stroh, deputy spokesperson for the National Security Council, had no comment on whether Golge’s name came up during Obama’s meeting. Biden’s office has not responded to multiple requests for comment.