It depends what is being posted. The contents of their file is work product and not subject to public disclosure at this time, but any actual evidence that is available to the public is obviously not confidential. If you are posting claims about someone being a criminal with no actual evidence to support it then you could be liable for defamation. But if you are posting criticisms of the police or the prosecutors for the incompetence, that is lawful.
This is not to be considered legal advice nor does an attorney-client relationship exist.
I don't follow you at all here - you are complaining that the suspect is publicizing his or her own alleged crime in which the charges were dropped? If so, I think they would have the right to make a true statement. If there is something more to it, the Prosecutor would know.
This is not legal advice but a general comment on society based on a limited set of hypothetical circumstances. No one should act or refrain from acting based on these comments without seeking appropriately licensed legal or professional advice. The author disclaims all liability in respect to actions taken or not taken based on his comments.