The German government ministry responsible for refugee processing received over 10,000 referrals of suspicious behavior by migrants in 2017, Die Welt reports.
In 2015, the number of migrants referred to the German security service was 571. In 2016, that number rose fourfold to 2,418. And in 2017 it rose again, fourfold to 10,597.
The cause of the increase is largely seen as a result of Chancellor Angela Merkel effectively dissolving the interior and exterior borders of Europe and opening up European countries to the Middle East and Africa.