For those who wish to see additional sources they are in my books on child abuse
Rav Yehuda Silman(Yeschurun volume 15 page 662): 5) It is obvious in these matters of child abuse that it not necessary to have formal witnesses. As we see in Bava Metzia (83) that R’ Eliezer bar R’ Shimon had the Romans arrest those who were drinking in the tavern and were sleepy. … The commentaries explain that the obvious reason for not needing witnesses but they could rely even on circumstantial evidence is because this was not a court procedure to punish wrongdoers. Rather it was either done to obey the law of the kingdom or it was to stop someone from sinning. The Rashba is cited in the Beis Yosef that witnesses are not needed in such a case…”. That is because we are concerned only with the knowledge of truth in order to stop the harm and to make protective measures against iniquity. Furthermore according to what I said that even a doubtful rodef is permitted to be killed it is obvious that it is permitted for us to take protective action even if we have unresolved doubts.
Rav Yehuda Silman(Yeschurun 15): Nevertheless the decision to report the perpetrator to the police is not given to everyone to decide. Rather as the Yam Shel Shlomo has said it is given to a rabbi or to a distinguished layman who will judge the matter objectively.[ R' Gottesman of the Aguda said we posken like this Yam Shel Shlomo and don't require a beis din]
Rav Yehuda Silman(Yeschurun 22): Question: I had previously received a query from America concerning the issue of informing the government authorities in a case of a teacher sexually abusing his student. The question was whether it is permitted or even a mitzva to be involved in reporting the matter to the secular authorities. I replied [Yeschurun 15 page 661] that there are number of different ways to judge the matter. 1) Viewing the abuser as a rodef (pursuer) [I mentioned in the previous article that this does not apply in the case of a male above the age of 13 or a girl above the age of 12 when the adult does it with their consent.]. 2) Stopping the abuser from sinning. I brought the dispute between the Ketzos and the Nesivos HaMishpat…and the Yam Shel Shlomo and the Chasam Sofer. However it is agreed by all of these sources is that a person of distinguished status (chashiv) is able to stop another from committing a prohibited act. 3) The position of Shulchan Aruch (C.M. 2) that a beis din is able to flog and punish in order to protect society – in a manner which is not prescribed by the Torah. Therefore in a case like ours in which experience has shown that a sex abuser is able to ruin many people – everyone agrees that beis din can punish in ways not prescribed by the Torah.[In the earlier article I pointed out there are significant differences between these approaches. If you take the perspective of separating the abuser from sinning then if the teacher is fired then there is no longer a need to act since he has lost his primary opportunity to sin but of course it depends on the nature of the crime. In contrast if the concern is protecting society then the perpetrator should still be reported even if he has been fired.] 4) The view expressed in Bava Metzia (83b) concerning R’ Eliezar bar Rav Shimon who was involved in capturing thieves because the king had commanded him to do so. I brought the dispute amongst the rishonim was to whether or not the halacha is in accord with R’ Eliezar or not. In the original article I was inclined to the view that in the case of sexual abuse since the perpetrator is not executed but is imprisoned to protect society then perhaps all would agree that it is permitted to report him to the authorities.
Rav Yehuda Silman(Yeschurun volume 15 page 663): The laws that have emerged from our discussion concerning child molesters. We see that there are two separate issues 1) Concerning removing the perpetrator from his job. In this issue we establish that the halacha follows the view of the Sho’el u’Meishiv that it is enough that there are bad rumors and there is concern because of doubts. It seems that in such a case where there seems to be a basis for these rumors it is possible to remove him from his job even in the middle of the year and he does not receive any compensation for the remainder of his contract or for loss of job. 2) Concerning reporting him to the secular authorities. If the circumstances are that it is sufficient to remove him from the job and there is no concern that he will continue attacking children, then that is what should be done and he should not be reported. 3) However if there is a concern that he will continue to molest children, then at least because of the requirement to stop him from sinning it is permitted to report him even if he does not molest in a way that he transgresses actual Torah prohibitions and is therefore not considered a rodef. But since in our days prison is not considered life threatening it is permitted to cause him to be imprisoned. 4) However the decision as to whether to report a molester is not given to everyone as the Yam Shel Shlomo said Rather it is given to a dayan or an important person. 5) Furthermore, the understanding of the facts of the situation as to what actions are needed can be based upon the evidence of children or any other evidence which arouses a serious question such as tape recordings, letters, or polygraph tests. In general without this - if there is no evidence even according to what is accepted by secular law – there can be no punishment. The point is that there is no requirement that the evidence must be valid according to the Torah. 6) However if the suspect is prepared to accept therapy that will make him better - such as psychotherapy, or chemicals which suppress his sex drive – if it seems to the dayan that he will do what he promised [and sometimes with appropriate supervision] then treatment is preferable to reporting him to the police. However even if the molester is given the alternative of treatment and supervision instead of jail - he needs to quit his job which involves contact with children. 7) Outside of Israel where secular law is relevant there are additional reasons to be lenient and allow reporting to the police. 8) It is a good idea to establish a dayan or a beis din to make the decisions about the above issues and therefore men should be selected for this purpose who are experienced in these matters because of the serious of the matter which requires special expertise.