Hopes are rising that American pastor Andrew Brunson may be freed, more than two years after he was first detained in Turkey, BBC reports.
Mr Brunson returned to court on Friday, with US media outlets reporting a deal had been struck for the North Carolina evangelical's release.
However, US Vice-President Mike Pence would only say "we remain hopeful".
Mr Brunson was arrested over alleged links to political groups following the failed 2016 coup attempt.
The latest hearing of his case is now under way in a court in the western province of Izmir.
The pastor, who has been under house arrest since being released from prison in July, denies charges of espionage. If found guilty, he faces up to 35 years behind bars.
His detention has damaged relations between Washington and Ankara, with both sides imposing sanctions on the other - resulting in the Turkish lira plummeting.