C.M. Frankie

What causes adults to kidnap children? The perpetrators range from serial rapists to parents trying to protect their sons and daughters.

Lee Boyd Malvo, part of the D.C. Sniper duo who terrorized the D.C. area in a series of murders, is serving life in prison without parole. But Malvo, who was 17 at the time of the killing spree, may be up for parole in 2022 due to a new Virginia state law.

Julie Williams, Lollie Winans, Paul Fugate and others are among those who have been killed in national parks and whose cases have yet to be solved.

Ken Rex McElroy, a bully who menaced the farming community of Skidmore, Missouri for years, was shot and killed on July 10, 1981 outside a local bar. Witnessing the murder were McElroy's wife and dozens of local residents. Yet the gunman has never been identified.

Aiyana Gauvin, Adrian Jones and Roman Barreras are some of the high-profile cases from the past few years of children who were abused and ultimately killed by their parents. We speak with experts about why some parents unleash such extreme violence on their children.