You can report a sex crime with any law enforcement agency but perfectly one that serve your area. If the case involves the online sexual exploitation of a minor, say for example when a suspect communicates with a minor using the social networking site or communicates with a minor using email, you can make a report to the National Center for Missing and Exploited Children. They'll complete a report for you and forward it to the appropriate law enforcement agency. I should also mention that there are certain members of the community, member of the public who are mandated reporters. They're people like doctors, nurses, social workers and teachers who are required to notify law enforcement officials if they become aware of any incidence of abuse. But it is preferred that report be made directly to law enforcement agency.