The only appropriate response to immigrant crime IMO:

Any immigrant who commits any anti-social crime worse than jaywalking during the first 20 years in his new home nation gets deported to his old homeland, no exceptions. If he or she has received a citizenship it is automatically revoked. The criminal is held in jail until the deportation can be accomplished. If it is unknown where he or she comes from, or if the nation of origin refuses to take back their own trash, then the criminal is sent to a nearby third nation if a deal can be struck (bribing other nations to take in these people is definitely worth it!). If no such deal can be made, then the criminal will sit in a concentration camp until the situation changes or until he or she dies. Any humanitarian complaints are passed on to the nation of origin, since it's their fault their trash has to be treated this way - they're free to take them back at any time.

Problem solved.