Ariz. family says they won't stop looking for girl

John Evander Couey, who took Jessica Lunsford from her home in Florida, lived just down the street. "He had an opportunity to stalk the family," Allen said. "He went in there for the child."

In the 2002 kidnapping of Elizabeth Smart in Utah, her abductor was a handyman the family knew and took her from her bed at knifepoint. Nine months later, motorists spotted her as she walked with her captors.

Investigations have changed since the days the milk carton was the best way to disseminate photos of missing children, as the world was reminded last week when authorities in New York reopened the 1979 case of Etan Patz. The boy was 6 when he disappeared while making his first unescorted walk to the school bus.

Now groups can quickly disseminate photos on the Internet and to the media in the hopes that anyone who may have seen something will come forward with information.

And while social media has worked miracles in spreading the word when a child goes missing, such tools are also used by predators to stalk young people, Klaas said.

"At the end of the day, if some guy out of nowhere sneaks into a little girl's bedroom and steals her without leaving a fingerprint, we're in a world of hurt," Klaas said. "It's like pulling a needle out of a haystack."

Cone reported from Fresno, Calif. Associated Press writers Leanne Italie and David Crary in New York and AP researcher Jennifer Farrar contributed to this report.