Repeat sex offender Joseph Duncan is accused of kidnapping the siblings.
Over the last year, convicted sex offenders have been arrested or convicted in other, equally disturbing cases.
And two experts say there's plenty that can be done to protect children that isn't happening at the moment.
Phill Kline, the attorney general of Kansas, is pushing for harsher and more uniform laws and enforcement of them nationwide, and Erin Runnion stresses better education of parents and kids alike about child molesters. She is the mother of Samantha Runnion, who was kidnapped and murdered in 2002.
"Additionally, (there are) inconsistent and weak penalties throughout the nation, as they relate to predatory activity on children."
Kline says the nation's attorneys general want those penalties toughened.