The court accepted a 78-page indictment alleging Topuz had "very intense contacts" with police officers who led a 2013 corruption investigation involving top government officials and their families. The indictment called him a "terror criminal."
The Turkish government alleged the investigation was a "judicial coup" attempt orchestrated by a Turkish cleric who lives in the United States and leads a network that Turkey has labeled as a terror group. The government also blames the cleric, Fethullah Gulen, for a failed 2016 military coup, but he denies involvement.
Topuz told authorities he had been in touch with the officers for narcotics investigations as part of his job. The indictment said the proposed prison sentence for attempting to overthrow the government was life imprisonment and for espionage, 15 to 20 years. Topuz is also charged with privacy violations and illegally recording personal data.
Topuz's lawyer, Halit Akalp, told The Associated Press his client rejects the accusations and said, "He has no links to the alleged crimes." His arrest increased tensions between Turkey and the U.S. in 2017. The two NATO allies suspended bilateral visa services for more than two months.
Relations worsened dramatically last year when U.S. President Donald Trump announced on Twitter increased tariffs on aluminum and steel imports, causing a nosedive of the Turkish lira, to pressure the country into releasing an American pastor.
Pastor Andrew Brunson, who lived in Turkey for two decades, was convicted in October for terror links but was allowed to leave the country after spending nearly two years in detention. On Thursday, a senior U.S. official said the diplomatic mission's "single most important priority is absolutely securing the freedom of our unjustly detained employees and the American citizens."
Hamza Ulucay, a translator for the U.S. Consulate in Adana, was convicted of aiding terror groups this week and sentenced to 4½ years in prison. He was released for time served following nearly two years in pretrial detention but is barred from leaving the country.
Another employee, Mete Canturk, is under house arrest and Serkan Golge, a Turkish-American NASA engineer, is in prison. The senior U.S. official, who spoke on condition of anonymity because of the sensitivity of the issue, said "we still have not seen evidence that would support charges against Hamza or Metin or Mete."
The arrests have been part of a widespread crackdown following the coup attempt. More than 77,000 people have been arrested and some 130,000 public employees sacked through emergency decrees. Critics say the purge went beyond the suspects of the coup with the arrests of journalists, lawmakers and activists.
Among the 30 complainants on the indictment against Topuz are Turkish President Recep Tayyip Erdogan and former ministers.