A North Carolina pastor who made Turkey his home for more than two decades has been held captive by the government for more than 500 days now.

Andrew Brunson was charged by the Turkish government with attempting to destroy the country’s constitutional order and overthrow their parliament. Brunson has been sitting behind bars since last year, swept up in President Recep Tayyip Erdoğan’s engulfing purge of perceived enemies. He has lost more than 50 pounds in custody.

Brunson and his wife, Norine, raised their family in Turkey and ministered through the Protestant Izmir Resurrection Church in the Aegean coast city. In October 2016, they found a note on their door telling them to report to the migration management office for what they thought would be a visit connected to their visa renewal. Instead, officials detained the couple.

Norine was eventually released and allowed to stay in the country. The pastor, though, was sent to jail in December 2016 on a hazy accusation of “membership in an armed terrorist organization.”

At a press conference alongside Turkish Foreign Minister Mevlüt Çavuşoğlu in Ankara last week, Secretary of State Rex Tillerson said the U.S. continues “to have serious concerns about the detention of local employees of our mission in Turkey and about cases against U.S. citizens who have been arrested under the state of emergency.”

“We will continue to engage with our Turkish counterparts to seek a satisfactory resolution to these cases, and we call upon Turkey to release Pastor Andrew Brunson and other U.S. citizens whom we believe are being unjustly detained,” Tillerson said. “With regard to Serkan Gölge, we believe his release through the appeals process would be both just and appropriate.

A NASA scientist working on the U.S. mission to Mars, Serkan Gölge was visiting his parents in Turkey in July 2016 when he was arrested in Erdoğan’s engulfing post-coup sweeps. Turkish authorities, claiming his NASA security card meant he has CIA links, threw him in solitary confinement and only let the physicist be seen by a U.S. consular official this October. Family later discovered through court documents that Serkan’s sister’s brother-in-law had been the tipster who turned in the NASA researcher over a family land dispute.

Gölge was recently sentenced to 7.5 years in prison. He is married with two sons and has been a U.S. citizen since 2011.

Çavuşoğlu replied that Turkey’s judicial system “does not receive any direction from any other third country or a political intervention from within.”

“The appeal process is open. You can go all the way up to the constitutional court,” he said. “We do have an individual application system to the constitutional court and even the European Court of Human Rights.”

State Department press secretary Heather Nauert said U.S. consular officials have been able to visit Brunson three times: Aug. 24, Sept. 18, and Feb. 6.

“He’s an American citizen; he’s been detained in Turkey well over a year now. I believe it’s – goodness, been closer to a year and a half, I believe,” Nauert said last week. “Secretary Tillerson, this is an issue that is important to him. I know that he has brought it up with the government, I know that the vice president and the president have in the past brought up that issue as well.”

The American Center for Law and Justice, which is representing Brunson in the United States, said earlier this month that Brunson and his Turkish attorney were able to formally meet with the prosecutor, but still hadn’t gotten access to the case file or indictment. He can be held up to seven years without being formally charged.

“Today was a hard day for Andrew. The prosecutor called him for more questioning/statement,” Norine Brunson wrote on the couple’s Facebook page on Feb. 7. “There was a previously scheduled meeting with someone from the consulate right afterwards so he was able to write me a note: ‘I am pretty shattered …I am very discouraged. Please have prayer for me.'”