When they get worse than citizens I'll say we have a problem, but it's not close.
The study looked at conviction data in Texas — which has the
second-largest population of foreign-born residents — for native-born, undocumented immigrant, and legal immigrant residents.
The research found that native-born residents were most likely to commit and be convicted of crimes, while illegal immigrants saw a conviction rate that was 56% lower. Legal immigrants appeared to be the most law-abiding, with 86% fewer convictions than native-born Texans.
There's also a Criminology journal
study from March which examines states' reported rates of violent crime and undocumented immigration. From 1990 through 2014, those data found a negative correlation — meaning that the more a population is comprised of undocumented immigrants,
the lower the violent crime rate seemed to be.