Actually, the article I read (on CNN) stated that the mom thought she was going to Canada with a friend and her family.
http://www.cnn.com/2006/US/06/09/myspace.runaway.ap/index.html
<SNIP>
"....
Katherine's mother, Shawn Lester, said her daughter had persuaded her in April to help her get a passport so she could go on a two-week vacation to Canada with a friend's family.
On Sunday, they drove to a bus station for that trip, but the family didn't show up. Shawn Lester said she called them, learned there was no trip and brought her daughter home. The next day, Katherine was gone...."