Illinois child custody laws????

[Bruce1]

Hi... does anyone have any info on the laws for Illinois re child custody??? My stepson's (16yrs old) mother sent him to live with us because he was having issues with her (in another state) and now it seems that she wants him back ..been about two weeks. He does not want to go and we (his father and myself) think it's best if he is here with us too. We have been told that the child does not have to go back if he does not want to but I can't seem to find the law on that one. Only thing I found was that the child's preference would be taken into consideration but was not the determining factor. Any help is much appreciated..thanks