I will repeat a point I have made countless times before. A child molester or rapist is a danger to the welfare of the community. He is reported to the secular authorities as preventative act of protection. The fact that the secular court will try him based on rules and procedures that are different than Torah or that they will punish differently then the Torah - is not a reason for not using them for protection. This fact is repeated by many gedolim - some of which are listed below. Many additional sources are found in my books on abuse - especially volume II. Furthermore not only circumstantial evidence is permitted but conviction based on a standard of less then absolutely certainty is also permitted - sofek rodef is treated as a rodef. [additional sources are in the commentary section]
In addition this case involved a mandated reporter who is required by secular law to report the alleged abuse. BM 83 provides a basis for requiring a Jew to comply with mandated reporting law. These issues have been discussed many times in many posts on this blog - as well as my 3 books on child abuse.
Steipler Rav (Within the Domain of Gedolei Torah Volume 2 page 557-560): … When Rav Lorenz told the story to the Steipler Rav, the Steipler screamed, “A Jew who sins and repeats that sin, it is better that he be punished in this world and not – G‑d forbid – in the World to Come.” He explained, “The punishment in this world is minor compared to what happens in the World to Come. Furthermore if you succeed in stopping the jail sentence he will continue to repeatedly commit this crime. It is better that he receive his punishment and perhaps learn self‑restraint…In addition if I give you permission and you testify for his benefit it is obvious that every newspaper and all the public media will publicize the matter and it will also be a chilul HaShem when he sins again…”
Rav Moshe Halberstam (Yeschurun 15 page 646): Let’s return to the original question concerning a wicked molester whose evil inclination forces him to sin and be wicked and it is possible to turn him over to the government in order that he be incarcerated in prison for a number of years until he calms down and returns to G‑d wholeheartedly. According to the sources we discussed before it is clear that there is no sin or transgression in handing him over to the authorities. In fact the opposite is true – it is a mitzva because by doing so he is caused to stop from doing the disgusting deeds. In addition we know that the government will not execute him. Therefore the essence of his punishment is that he will be forced to dwell for a number of years in prison. This will be beneficial to him in that they will assign him a psychologist or psychiatrist who will supervise him and his activities with a watchful eye. Perhaps he will be able to find a resolution of his torment by means of this treatment. So in such a case it is obvious that it is a good thing to save him and to save his family from his incestual attacks on them.
Rav Yehuda Silman (Yeschurun 15 page 662): … 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 22): …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. Furthermore in the original article it was concluded that that it is obvious that there is no need to have witnesses that meet the standards required by the Torah but even less than that is sufficient and I cited a number of rishonim. The reason is reporting the teacher to the secular authorities is not punishment requiring a beis din but is an action mandated by secular law (in the Diaspora) or in order to separate the abuser from committing sin. In addition according to the reason that even in the case of a possible rodef it is permitted to inform the authorities – it is obvious that is permitted without proper witnesses since all that is required is that there be the possibility that he is an abuser….some say just the opposite and assert that it is not necessary to convene a beis din with both sides present and that in fact a beis din or even a rav is not needed at all. Rather what is needed is to involve the government authorities as soon as possible since only they have the legal right and actual ability to deal with these matters…. On the one hand concerning the legal requirement - it is clear that there is no need to convene a beis din in the presence of both sides since the basis of the permission to report the perpetrator to the secular authorities is either because he is a possible rodef (pursuer) or to separate him from sinning or because of the government mandates reporting
Rav Yehuda Silman (Yeschurun 22): 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... 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... In addition according to the reason that even in the case of a possible rodef it is permitted to inform the authorities – it is obvious that is permitted without proper witnesses since all that is required is that there be the possibility that he is an abuser...it is clear that there is no need to convene a beis din in the presence of both sides since the basis of the permission to report the perpetrator to the secular authorities is either because he is a possible rodef (pursuer) or to separate him from sinning or because of the government mandates reporting. In fact these cases do not require a beis din and we need to merely consider the possible loss versus the possible gain. If the accusations are in fact true then we are dealing with a case of saving a person from being harmed. While if the accusations are in fact not true then in general, the government will free him. On the other hand it is certain that it is impossible that everyone can take responsibility for deciding whether to inform the secular authorities…