GOLDEN, Colo. -- Mindy Sigg sat sobbing on Thursday, listening to prosecutors tell a court that her 17-year-old son had confessed to the abduction and killing of 10-year-old Jessica Ridgeway.

While any mother would be devastated, there was an even more heartbreaking wrinkle for Sigg: She was the one who called police.

It was not the only high-profile case this week in which a mother made that painful choice. In New Jersey, Anita Saunders saw something on a Facebook page that led her to call police.

Her two sons, ages 15 and 17, are now charged with killing 12-year-old Autumn Pasquale, a bike-lover who authorities said was lured to their home with the promise of new parts.

What does it feel like to turn in your child, knowing they could be sentenced to many years in prison? Surely, no one knows but those who've done it.

But a main motivation, according to one criminologist, is simply a desire to do the right thing.

"These are law-abiding people, pro-social people," said Kathleen Heide, professor of criminology at the University of South Florida. "And besides doing the right thing, the parents often want to get their children help."

What they often aren't aware of, though, are the full ramifications in terms of likely punishment.

"If these are cases of first- or second-degree murder, in most cases the kids will be charged as adults," Heide said. "This means they can be sentenced to life in prison."

Certainly not all parents are ready to turn in their kids. One high-profile case from the 1990s, in fact, resulted in strains between the United States and Israel, when a father helped his teenage son escape this country after a particularly brutal murder in Maryland. The son, Samuel Sheinbein, confessed and is now serving a 24-year sentence in Israel -- a lighter term than he likely would have gotten in the United States.

Mindy Sigg made a different decision. Reached by phone Wednesday, she told The Associated Press: "I made the phone call, and he turned himself in. That's all I have to say." Then, she broke down in tears.

Her son Austin Reed Sigg made his first court appearance Thursday in the death of Jessica and in a separate attack on a 22-year-old runner, who managed to break free, in May.