Mehmet Öztürk had blown himself up on İstiklal Avenue off Taksim Square on March 19, 2016, killing four people, including three Israeli citizens, and injuring 44.
Five suspects arrested in connection to the attack appeared in court on Friday. Çapkın, who is accused of being a member and leader of a terrorist organization, was released due to his health condition in the first hearing of the case.
The suspects attended the trial via video link, with Çapkın reportedly repeating his first testimony rejecting all charges.
His brother, Ercan Çapkın, also said he has no relation to IS or the attack.
I do not know Mehmet Öztürk who staged the attack. I did not go abroad with legal or illegal ways. I did not use and code name except my real name.
Aysu Yılmaz, a lawyer for controversial anti-Darwinist Islamic sect leader Adnan Oktar, also attended the trail, claiming that one of the suspects, Hüseyin Kara, was involved in a conspiracy against Oktar.
The court, however, rejected Yılmazs demand to participate in the case.
It also ordered the other four suspects in the case to be kept in custody and postponed the trial.