Anis Amiri, 23, left his native Tunisia in 2011, soon after the outbreak of the so-called Arab Spring there. He lived in Italy for three years before arriving in Germany in July 2015. In April of this year, he applied for an asylum in Germany. According to German authorities, Amiri was arrested multiple times in Tunisia for drug-related offenses. He is also believed to have used at least six different aliases since moving to Europe, and to have claimed to be a citizen of Lebanon and Egypt at different times.

On Wednesday, German newspaper Süddeutsche Zeitung revealed that Amiri's cell phone and email accounts had been monitored by German security agencies at least since January of this year. The decision to monitor his telecommunications was reportedly taken by officials at Germany's Center for Terrorism Defense (GTAZ). The agency functions as a fusion center for intelligence cooperation between German police and spy services. The newspaper said that Amiri was deemed suspicious because of his connections with several radical Islamists, who were arrested in Germany in recent months.