I reference a large body of research showing the almost exclusively positive effects of immigration (legal and illegal), but you still think you know better. Illegal immigrants made legal also contribute in a positive way, so all you've said here is a good reason to legalize the 11 million immigrants of the USA, as mentioned in the specific study I quoted here. What you should do, before boldly contradicting all the research on this subject, is ask yourself exactly why fugitives, economic or otherwise, are branded as "illegal," and why you feel the need to brand them "criminal," a classification usually reserved for people who steal, murder, rape and so on.