How do I turn in a man posing as a bisexual woman?

I found a craigslist personals ad for a 23 y/o bisexual woman looking for another woman (the ad requested photos) so I responded, but did not send photos. I now have documented proof that the individual who posted the ad is a man trying to elicit photos from girls. Where can I turn him in so he doesn't continue to do this to other girls?