Wrong. There is a scholarly consensus that immigrants in general – legal and illegal –commit fewer criminal offenses than U.S. citizens, but that is only because the legally admitted immigrants have a much lower crime incidence than the native-born population and outnumber the illegal aliens by three to one. That statistic based on the combined foreign-born population, disguises the incidence of criminality by illegal aliens alone.
My study of the crime incidence among illegal aliens (here http://www.fairus.org/site/docserver/crimestudy.pdf) found that illegal aliens were incarcerated in state and local prisons and jails at a 50 percent higher rate than for a comparable native-born population. They also are a large majority of federal prisoners. That study was based on data reported by state and local authorities to the federal government when seeking federal compensation in the State Criminal Assistance Program.
The takeaway is that even the supposedly expert commentators may be wrong.