You can report suspected offenders to local authorities.
If you know the nationality of a suspected offender, you can also report them to their embassy and they can face prosecution by their country. Submissions are forwarded to appropriate local and international law enforcement agencies for investigation. All tips are treated with the utmost security and privacy.
Please provide as much detail as you can.
Responsible Tourism, a project of The Future Group - http://www.thefuturegroup.org