Simon : One thing I find slightly odd, why isn't the mother guilty of failing to report it?
While the mother may have had a social responsibility to report the abuse, she was not legally obliged to do so. Those legally obliged to report ("mandated reporters") are most professionals in education, health care, law enforcement and social work. These professionals are listed in the Abused and Neglected Child Reporting Act, particularly in section 4 (Persons required to report). The exceptions are privileged communications between an attorney and his or her client, and a member of the clergy (or practitioner of any religious denomination) who hears a confession in his or her professional character or as a spiritual advisor (Section 735 ILCS 5/8-803).
There may be a number of reasons her mother did not report it to the police. The perpetrator was a relative and lived with the family so that may have influenced her decision. He needed an interpreter in court so if they were immigrants that may also have been a factor. In addition, it seems that she also only knew of the initial abuse (which involved touching) and thought it had been dealt with and had ended.