German state police detained a teenage asylum-seeker they believe may have been planning a terror attack. The 17 years old, who entered the country illegally in 2015, was detained on Tuesday in the village of Gerswalde after authorities learned he sent a goodbye message to his family through WhatsApp, telling them that “he had joined the jihad.” He was staying at a center for migrants and refugees that hosts unaccompanied minors. He’s been living there since 2016. German Chancellor Angela Merkel’s open door policy has seen more than 1 million asylum-seekers enter the country since 2015. Officials believe the teen was planning a suicide attack in Berlin, though Bradenburg police spokesman Torsten Herbst told at this point in the investigation that “evidence of the planning of a concrete act has not yet been identified.” The state Interior of the Minstry’s office identified the suspect as Syrian, though authorities tell it is possible he falsely registered that way. Investigators are looking into whether he is actually from a country in North Africa. Herbst told the teen is in the process of being interrogated, his identity has not been released. The arrest comes a week after a suicide bomber killed 22 people and injured scores more at an Ariana Grande concert in Manchester and months after a man drove a truck through a Berlin Christmas market. The Islamic State claimed responsibility for the holiday attack, which left 12 dead and dozens more injured.