While investigating the phone records of two civilians captured at a military base at the heart of the 2016 coup attempt, authorities discovered how the Gülenist Terror Group (FETÖ) planned the attempt in the Pennsylvania compound of the group's leader, Fetullah Gülen.

Gülen, the prime suspect in the trials on the coup attempt that killed 250 people on July 15, 2016, is accused of orchestrating the plot and masterminding the effort to seize power. New evidence shows he was in direct contact with Hakan Çiçek, a FETÖ figure who was captured in Akıncı military base in the capital Ankara during the coup attempt. Çiçek's phone records show that the terrorist group's leader had a FaceTime call with Çiçek for about three and a half minutes when the latter was still on the military base.Officials investigating the phone records found that Çiçek, owner of a FETÖ-linked college in Ankara, activated his new cellphone first in Gülen's compound when he visited the well-guarded place in Saylorsburg, Pennsylvania on March 7, 2016. Gülen has been living in the United States since 1999. Investigators say the cellphone was handed to Çiçek by senior FETÖ figures to be used for communication during the coup attempt.

Çiçek is also accused of attending meetings to plan the coup attempt carried out by FETÖ's infiltrators in the military. Others who attended the meetings were Adil Öksüz, Kemal Batmaz, Harun Biniş and Nurettin Oruç. All were captured while trying to flee from Akıncı base when the coup was foiled due to a strong public resistance. Öksüz, along with Biniş, also attended meeting with putschist generals in the capital Ankara shortly before the coup attempt, according to eyewitnesses. All five men had visited the United States around same time between March 17 and March 23, 2016 flight records show, though they kept their travel secret and took different flights, investigations have uncovered.

Earlier findings in the investigation had indicated that Çiçek repeatedly called Abdullah Bayram, a top FETÖ figure who stays in Gülen's Pennsylvania compound, while the coup was underway. His text messages urged Bayram to put him in touch with Gülen. Gülen later had a video call with Çiçek, according to investigators.

Clinging to former U.S. President Barack Obama's lack of action against FETÖ, the current U.S. administration has dragged out the extradition process for the terrorist group's leader wanted by Turkey. Ankara, meanwhile, hopes Washington will change its mind with more evidence clearly linking Gülen to the coup attempt. Turkey already sent a large cache of evidence to U.S. officials implicating FETÖ in the attempt.

Çiçek spent the night of July 15, 2016 at the Akıncı air base where putschists dispatched warplanes to strike the presidential complex and other strategic locations. He was arrested along with his companions Öksüz, Batmaz, Biniş and Oruç, but Öksüz managed to flee when a court later released him in a controversial verdict. The others remain in jail.

A U.S. delegation recently visited Turkey to discuss the extradition process and evidence on FETÖ's involvement in the coup attempt. The United States' apparent reluctance to extradite Gülen has angered Ankara, which has called on Washington to stop "stalling" the process.