I would probably talk to the local district or prosecuting attorney's office, and expect them to do whatever follow-up may be warranted. Even though the sites do not apparently meet the legal definition of pornography, from your description of the URL's they apparently are sites designed for pedophiles. It is very disturbing that this individual actually logged onto these sites at a public library, and suggests that the children in the community are potentially at risk from this person. Where pedophilia is concerned, I think your first responsibility is toward the protection of the children of your community. The patron's right to privacy, etc. takes a back seat.

Will eagerly await your post re: what action you actually did take.

Janie