The United States on Wednesday called on Turkey to release businessman and philanthropist Osman Kavala, who was arrested for what the US called "specious" charges related to the 2016 failed coup and 2013 anti-government protests.
The US State Department called for Kavala's "immediate release."
"The specious charges against Kavala, his ongoing detention, and the continuing delays in the conclusion of his trial, including through the merger of cases against him, undermine respect for the rule of law and democracy," State Department spokesman Ned Price said in a statement.
"We urge Turkey to abide by the European Court of Human Rights’ rulings and ensure a just, transparent, and speedy resolution to the case in line with its domestic laws and international obligations."
Kavala, a well-known figure in Turkish civil society, has been jailed since October 2017. He faces a potential sentence of life in prison for allegedly trying to overthrow the government of President Recep Tayyip Erdogan in the July 2016 failed coup attempt, including espionage charges.
Those charges were recently combined with a case surrounding his roll in 2013 anti-government protests.
He was originally acquitted in the protest case, but the decision was overturned in an appeals process last month.
Kavala continues to reject the charges, and rights groups believe Erdogan's government is trying to make an example out the 63-year-old to other civil society leaders.
He is best known for his support for cultural projects on minority rights, Kurdish affairs and Armenian-Turkish relations.
Erdogan frequently refers to Kavala as a Turkish representative of American billionaire George Soros, a favorite conspiracy-theory scapegoat of authoritarian leaders around the world.
Turkey describes American researcher Henri Barkey as a co-conspirator of Kavala, and Barkey is also on trial in absentia for his alleged role in the 2016 coup.
In the State Department statement, Price also condemned Barkey's inclusion in the "unwarranted" legal proceedings in Turkey.
"We believe the charges against Dr. Barkey to be baseless, and we call on Turkey to resolve his case in a just, transparent, and rapid manner," he said.