There are three types of cases that are important.
1) There are suspicions that abuse took place or there are suspicions that someone is an abuser. What is missing is evidence but the evidence can be obtained by competent investigation.
2) the facts are well known or the evidence is solid that abuse took place and the identity of the abuser is known. The problem is what to do with this according to the halacha and secular law. These two cases are dealt with at length in my book. However there is a
3) third type of case which is much more problematic. That is where the evidence is not known - either regarding whether abuse happened or whether the suspect in fact abused the child. Or alternatively there is conflicting evidence. This happens in divorce cases where where the wife accuses her husband of abusing the kids. She might even claim that she witnessed it. The husband denies it. In addition there are cases of abuse where the police investigate and say that they don't have sufficient evidence and therefore close the case.
In both these cases claims have not in fact been disproven - but they haven't been proven either. Many times the beis din, police or the secular court system will simply say there is nothing that they can do because of lack of evidence and they close the case.
The suspect has not in fact been declared innocent. What should be done with the suspect?
According to the judicial model (both Jewish and secular)- since there is no case it is equivalent to saying he is innocent. In fact if there aren't two kosher witnesses - the charges are not allowed to be made public. However according to the defense against harm model - the suspected abuser can not be trusted and restrictions or supervisions are necessary.
If he is a teacher or someone who deals with children - he can not be allowed unrestricted access to the children and there are solid grounds for dismissal simply because of the charges. If he is a parent then there needs to be careful monitoring of the children. These are difficult cases to deal with - especially since both sides usually have proponents who feel very strongly that they have the truth.