Germany has been accepting much more immigrant refugees than other European countries, out of moral duty but also out of economic interest. Germany has had pro-immigration programs for years before that, especially after the great recession, because the country has a deficit of young working-age people to contribute to their economy.
Some refugees have committed crimes and offenses, as it is likely to happen from any large group of people. I have yet to see any evidence that they do it in higher proportion that european-born population.
You can take any anecdote and turn it into fear-mongering. Before we had refugees, romani people were the target of choice, before that, south-europeans. Nationalists have always found a convenient scapegoat.
And by the way, there is no evidence that immigration, even mass choc-wave immigration, has adverse effects on the economy of a country.