I'm not going to editorialize on these GAO (General Accounting Office of the United States Government) studies on the criminal aspects of illegal immigration. Suffice to say, there is a cost (both in lives, victims and incarceration costs). These are links to two GAO .pdf files analyzing the criminal costs of illegal immigrants (you'll need adobe acrobat reader to read them):

www.gao.gov/new.items/d05337r.pdf


www.gao.gov/new.items/d05646r.pdf