Öztürk's father and brother were also detained by police in the aftermath of the attack.
Born in 1992 in Gaziantep, Öztürk was sought as the Islamic State (IS) suspect from ‘terror-qualified missing person' list. The identity of Öztürk was confirmed following DNA tests of samples taken from his relatives.
Öztürk's father reportedly said that the man in video footage of the attack looked like his son who had long been thought to be missing in Syria but was recently reported to be in Istanbul.
Police and intelligence units had focused its search on two IS suspects over the Istanbul attack; one suspect was Savaş Yıldız who was among four IS members currently being sought in Turkey, while the other was Mehmet Öztürk who appeared on surveillance cameras in the attack.
The March 19 assault on central Istanbul's İstiklal Avenue killed five, including three Israelis and one Iranian, and wounded 36 others.