Ankara: A former NASA scientist sentenced in Turkey to over seven years in prison on terrorism charges was suddenly freed without an explanation, hours after a phone call between Presidents Donald Trump and Recep Tayyip Erdogan.

Serkan Golge, 39, is a Turkish-American citizen who was arrested while on vacation visiting his family in southern Turkey in 2016, in the aftermath of a coup attempt that failed to oust Erdogan, The New York Times reported.

He was convicted in February 2018 and sentenced to seven and a half years in prison, which was later reduced to five years by an appeals court.

Golge, his wife Kubra and their two children, all Americans citizens, were barred from leaving the country.

Kubra, told The New York Times on Wednesday night that he had just walked free from prison and was heading back with his parents to their home in the city of Hatay.

“I just talked to him on the phone. He is going back to his family,” she said. “He was shocked.”

Trump and Erdogan spoke by telephone earlier on Wednesday and discussed “a number of bilateral issues”, such as trade and tariffs, according to a White House deputy press secretary, Judd Deere.

An official White House statement of the call did not mention Golge.

A release sent out to the media by a Turkish official in Erdogan’s administration also did not mention Golge. It said the Presidents discussed a range of issues, including Turkey’s planned purchase of the Russian S-400 missile defence system, which Washington opposes.

Turkey detained more than a dozen American citizens, including Golge, as well as three Turkish employees of the US Consulates, in a crackdown after the failed coup.

Some 70,000 people remain imprisoned in the widespread, three-year crackdown after the attempted coup, while another 150,000 public employees – academics, judges, and police and military officers – have been purged from their jobs.