Phone records have been revealed during the investigation into Turkey’s deadliest terrorist attack, suggesting a degree of cooperation between İlhami Bali, the alleged Islamic State (ISIS) leader in Turkey, and Turkish armed forces.

Bali, a Turkish national from the southern province of Hatay, is regarded as the ISIS “Emir” or leader of operations in Turkey. As a U.S.-led coalition with Turkish participation began to strike ISIS targets in Syria and Iraq during the summer of 2015, Bali gave the order to go to war with Turkey.

His cell is held responsible by Turkish prosecutors for at least two bombing attacks that year: the attack that killed 35 mostly Kurdish activists in the town of Suruç in June, and the suicide bombings in Ankara that killed 109 Turkish citizens in Turkey’s deadliest terrorist attack.

Turkish left wing website sendika.org has published phone conversations released in the investigation into that attack reveal that throughout the same period, Bali was in contact with Turkish soldiers on the border. The conversations suggest a certain extent of cooperation between the two sides.

In one, dated Sep. 2 2015, Bali appears incensed that Turkish soldiers had caught and beaten one of his fighters.

“[Turkish] soldiers came over to this side and took one of our Turkish brothers,” Bali tells an unidentified interlocutor, presumably from the Turkish military or security forces. “They beat him black and blue. He’s standing next to me – show that to your commander.”

The ISIS leader explains that he is particularly angry because, he said, Turkish soldiers had called him “asking for help” before going on to beat his men.

Bali goes on to promise that he would find and shoot through the head a Turkish soldier who had gone missing the previous day. Bali is likely referring to Sefter Taş, a Turkish soldier who went missing on Sep. 1 2015, and was later burned alive in a filmed execution by ISIS.

The issue of the beaten ISIS militant continues to be a sore point for Bali, prompting his interlocutor to try to calm him down by recalling his “good treatment” of Bali. “Let’s not get down the wrong track for the sake of one or two people.”