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.
Runnion agreed, adding, "The major weapon that we have is awareness and communication with our children. The first step is to learn more about child molesters, more about how we can better protect our children. …Be aware that 95 percent of all children who are sexually abused know their predator. They know and trust the person who hurts them."
She started The Joyful Child Foundation "to raise awareness in every house across this country so that we can better protect our children."
Kline noted, "All too often the predator, such as Mr. Duncan, who is accused of this most recent crime, has acted out before and society has let them have a pass or back out on the streets. Statistics and information will demonstrate to that you those who prey upon children will act again. The Department of Justice estimates that the average pedophile commits 16 offenses while on probation.
"And many times these children are a silent victim in that they do not know where they can achieve help, how to speak out. And we have to be ready to hear that silent cry as they face victimization again by not allowing it, and keeping predators behind bars."
Kline gave an example of inconsistent penalties: "In Texas, if you commit a second offense, you won't see the light of day again. In Kansas, we had a 28-year-old man rape a 6-year-old boy, videotape it, place it on the Internet, and receive probation.
"This is unacceptable. We need to strengthen those penalties nationwide."