On June 5, 2015, pro-Kurdish HDP had a rally in Diyarbakır, a south-eastern Kurdish province in Turkey, before the parliamentary election. Explosions ripped through thousands of people gathered for the rally, killing 5 and injuring more than a hundred.
Burhan Gök, one of the perpetrators of the attack, was accused of aiding Islamic State militants' border crossing. Gök was released on trial with the verdict of 'no suspicion of escape', local media reported. Not even a judicial control decision was given about Gök.
HDP lawyers objected to the verdict on the grounds that the mobile phone and other evidence belonging to Gök had not been examined, and no HTS analysis had been conducted on Gök's mobile phone. HDP lawyers noted that there were statements of rally participants identifying Burhan Gök and that these statements had not been taken into consideration.
Lawyers also noted that according to the expert reports, there is high doubt that one of the men who speaks to Mustafa Kılınç is Burhan Gök himself. Therefore the court gave the verdict that the mobile phones of Kılınç and Gök to be examined. Kılınç and Gök had been captured in one of the anti-ISIS operations as both men were together with three men of non-Turkish origin. Kılınç and Gök had been accused of aiding these men's border crossing to ISIS camps in Syria.
When it had been later found that Gök was in contact with Orhan Gönder, the perpetrator of Diyarbakır attack, Gök was also included in the investigation of the attack.
In the criminal charge against Gök and Kılınç, it was stated that these two men aided the accommodation of Orhan Gönder before he went to ISIS camp in Syria. Moreover, when Gök had been captured, he was with İbrahim El Bakraoui, the perpetrator of Brussels blast in 2016. Gök had been accused of aiding the border crossing of El Bakraoui to ISIS camp in Syria.
El Bakraoui had been deported after he was captured with Gök. Later, El Bakraoui went to Brussels and organized the bomb attack in Brussels on 22 March 2016. El Bakraoui's brother Halid also organized the metro blast on the same day. Both attacks caused the death of 31 and injured at least 260.