Two years after the plan to topple the government, Gülenists are set to appear before courts in 2016 in a string of trials for the Gülenist Terror Organization's (FETÖ) "parallel structure."

The Gülen Movement evolved from a religious community running a network of schools and companies in Turkey and around the globe, to a criminal organization bent on grabbing power in Turkey, according to several indictments.

The movement's leader, Fethullah Gülen, a former imam who has lived in the United States since 1999 in self-imposed exile, is the main defendant in the cases against Gülenists.

The trials cover a wide range of accusations against the group, from plotting to oust the government and illegal wiretapping, to espionage. They are the culmination of investigations by the Istanbul Chief Prosecutor's Office and ensuing operations that have seen detentions of police chiefs and judiciary members allegedly associated with FETÖ, the name used to designate terror-linked members of the movement in the indictments.

The first trial against Gülenists in Istanbul already started last week. Gülen and 33 others, including nine jailed defendants, are charged with plotting against the Tahşiye group, a religious movement known for its opposition to Gülenists. The leader of the Tahşiye group, Mehmet Doğan, and 122 others were detained in 2009 in what was later discovered to be a plot by police officers and prosecutors linked to the Gülen Movement. The defendants in the case were later acquitted and released after an investigation found they were detained on the basis of forged evidence used to portray their group as a terrorist organization.

Along with Gülen, Samanyolu Media Group CEO Hidayet Karaca and former police chiefs Ali Fuat Yılmazer, Yurt Atayün and Ömer Köse are on trial. The Samanyolu Media Group is a media conglomerate tied to the Gülen Movement. The indictment asks for Gülen and Karaca to serve sentences on terror charges that carry multiple life terms.

After a second hearing, a court in Istanbul adjourned the trial to Feb. 23. Gülen was absent for two hearings and it is unlikely he will return for the third. His lawyer told the court his client was ready to testify in the United States, but the court rejected the appeal. An arrest warrant was already issued for Gülen, who lives in Pennsylvania in a compound belonging to an organization run by his movement. But Turkish authorities say it would take time to request his extradition from the United States due to lengthy bureaucratic procedures. Turkey and the United States have an extradition agreement for criminals, but Ankara needs to first finalize a "red notice" for his extradition to Turkey.

Istanbul prosecutors first launched operations into FETÖ in July 2014 for espionage and illegal wiretapping. Several prominent police chiefs were indicted by prosecutors on terror charges, which carry aggravated life sentences. On Feb. 15, police chiefs linked to the movement will appear before a court for the first hearing of their trial.

Gülenists are accused of illegal wiretapping thousands of people through infiltrators in the police and judiciary for blackmail and espionage.

Another trial of Gülenists scheduled for February is related to Selam-Tevhid, accused of being a terrorist organization, which turned out to be a disguise for Gülenists to illegally wiretap prominent figures. Police chiefs are accused of assigning false names to hundreds of people ranging from journalists to businesspeople and designating them terror suspects to justify wiretapping. A total of 122 defendants, including Gülen, a journalist and a police chief, will stand trial.

In January, Gülen and others will be tried for irregularities in the Dec. 25 probe, referring to that date in 2013 that is regarded as the second attempt to overthrow the government. Gülen and 68 others will be summoned to the court for the first hearing of this trial on Jan. 6. They are accused of forgery of evidence in the Dec. 25 probe.