Katherine Lester's parents thought they had no reason to doubt their daughter when she told them she needed a passport for a trip to Canada with friends.
The 16-year-old Gilford, Mich., honor student had never deceived them.
However, Lester really needed the passport to head to Israel's West Bank, one of the most dangerous parts of the world, to meet a 25-year-old man whom she had met on MySpace.com.
Lester apparently flew to the Middle East last Monday. At first, her family had no idea where she had gone, and made a public plea.
"Please come home. Katherine, please. We need you," said her sister, Mary Lester.
Soon the FBI unraveled the mystery. It seemed that Lester had been corresponding for about three months with a man on MySpace.com.
Her MySpace.com profile says she's from "Small Town, Michigan" and was accessible only to people on her "friends" list.
"She had met someone that she really seemed to care for quite a bit and wanted to go meet with him," said FBI official Dan Roberts.
MySpace.com was co-founded by Tom Anderson and Chris DeWolfe in 2003. They intended for it to be a place for established musicians to network and for unsigned musicians to get noticed.
It has exploded into a collection of personal pages and message boards, with 72 million active users. It is now owned by Rupert Murdoch's News Corp.
"There are lots of good things about MySpace," said Atoosa Rubenstein, editor in chief of Seventeen magazine.
"It's a great way to meet people with similar interests, or to stay in touch with friends who move away. But with sites like MySpace, children need to know that there is no way to check that people are who they say they are," she said.
"Anyone can go online and say they are a 15-year-old girl or a 25-year-old man. It's easy to grab photos and pretend you are someone else."
The site has survived several complaints that it puts young people at risk by making their personal information accessible by anyone, including online predators.
In recent months, MySpace has repeatedly made national news for its perceived role in child abduction cases. Profiles sometimes include everything from home addresses and phone numbers to photos of girls in provocative poses and kids hoisting whiskey bottles.
Rubenstein said it was parents' responsibility to make sure their teens safely surfed the Web. They need to realize that there is a new reality that did not exist when they were kids.
Rubenstein suggested that parents create their own profiles to monitor their children's' online activities.
"A computer is not a kid's baby sitter," she said. "Parents need to be aware that going online is a completely new situation that no generation has faced before. And parents of today's kids have to come up with solutions for these brand new problems."
"You don't want your children hanging out with the wrong crowd -- and these Web sites are even worse than that. Some of them are the wrong crowd devoted to the wrong topic," Rubenstein said.
In a statement, MySpace.com's chief security officer Hemanshu Nigam said, "We take seriously our responsibility to provide a safe and well-lit community for all our members. Every page of our site provides a direct link to safety tips. … The Internet is a powerful tool for connecting people with one another and, at the same time, parents are learning that they must teach their teens how to be safe and smart online."
Even though MySpace.com posts safety tips for parents on the site and provides safe links to the Web sites for online safety groups, it can't verify your age or your name.
It's entirely an honor system. It is possible to report lewd photos or hate messages, but the community of users must police themselves. Users 13 and under are banned.
Authorities say Katherine Lester flew from Detroit to New York and then headed to Israel. The FBI tracked her flight and persuaded her to get off the plane during a layover in Amman, Jordan. On Friday, she returned home to Michigan to her family.
Although it doesn't appear that Lester has broken any laws, the FBI is eager to find out more about the man the teenager wanted to meet.
"We don't know that he had represented himself accurately," Roberts said. "We believe there are millions and millions of juveniles working on the Internet every day, and so parents have to know what their kids are doing."
Here are Rubenstein's tips for protecting children from dangerous online activity :
Talk about online dangers with your children.
Bookmark safe Web sites.
Act on hunches and be nosy.
Learn about the new reality of the Internet yourself.
Reported by ABC News's Taina Hernandez on "Good Morning America."