There are different statutes of limitations (that vary in different venues) for different Tort (civil) and Criminal actions -- there is no statute of limitation on murder, the statute of limitations in Texas for criminal child abuse is 5 years I read.

As to the molestation cases that are 20, 30, 40 years old I am not sure how the courts gained jurisdiction after so many years -- the statute of limitations would be for criminal indictment and not trial time.