Should be reported by the victims, certainly not by a third party who has no first hand knowledge of the crimes.
I agree that it would be better coming from the victims. But if someone knows of or suspects a crime, filing a report to the police for investigation is a proper course of action to take.
Victims may have several reasons for not reporting a crime committed against them. This does not mean others should not report what they know or suspect - and the reporters are protected from a defamation claims regardless of what an investigation discovers as long as the reports were made without actual malice.