Turkish officials have identified the perpetrator of Saturday’s suicide bomb attack on a shopping district in Istanbul as Mehmet Ozturk, a Turkish citizen from the southern city of Gaziantep.

According to Turkish Interior Minister Efkan Ala, “the evidence at hand shows that he is connected to the Daesh terrorist organization.” Daesh is another term for the Islamic State.

CNN reports Ala added that the Turkish government is “still considering with great sensitivity other connections or forces behind this.” In other words, despite this unspecified evidence linking the bomber to ISIS, he could have been working for some other terrorist organization, such as the militant Kurdish separatists currently fighting against the Turkish government. There has not yet been a formal claim of responsibility for any group for the attack.

Ynet News reports Ozturk was identified through DNA samples and says he was “known to Turkish security forces as a member of ISIS.”

AFP reports that two of the five people arrested by Turkish authorities in connection with the bombing were Ozturk’s father and brother.

CNN notes that one separatist group, the Kurdistan Freedom Falcons (TAK), claimed responsibility for last week’s car bomb attack on Ankara and has explicitly threatened to target foreigners with further attacks. “Tourism is one of the important sources feeding the dirty and special war, so it is a major target we aim to destroy,” the group explained in a February statement, after a previous bombing.

On the other hand, the New York Times recalls that ISIS was responsible for a suicide bombing in the historic district of Istanbul in January, whose victims were mostly German tourists, and ISIS is linked to the massive bomb attack on a peace rally in Ankara last October, which killed 103 people.

AFP notes political tensions are growing in Turkey after the string of bombings it has suffered, with opposition leaders accusing the government of incompetence for permitting so much bloodshed. The Interior Minister was careful to state that Ozturk was “not our wanted list” during Sunday’s press conference, while conceding that his name was known to security forces.