Who is 'criminal' is fairly arbitrary in many cases. Say you sell some hash to a friend. Legal in some states, can lead to 30 years in some others, generally not a huge crime in the sense of harming others.

You should probably edit your original post, because this point is not at all clear from that post.

If controlled for factors such as social status, income, education statistics indicate that migrants are neither more nor less criminal than germans - a fact that I personally do not find surprising. Certainly there's now more crimes in absolute numbers since there are more migrants, but well - that's not surprising either. We also do have sufficient "european" crime to around, the mafia, east european gangs breaking into flats etc, and on top we have sufficient amounts of good old german crime - we're good at tax evasion, cheating on libor rates etc. All in all I'm not afraid that migrants will push german criminals out of their jobs.