Would You Rat Out a Loved One?

— -- Police this week halted a potentially deadly bomb plot at a South Carolina high school after an 18-year-old senior was turned in by two very unlikely informants: his parents.

Ryan Schallenberger was arrested Saturday after his mother and stepfather alerted authorities that a package containing 10 pounds of ammonium nitrate, an easily obtained but highly explosive substance, had arrived at the family's home. It was later discovered that the straight-A student had plans for an attack he referred to as "Columbine III," according to police.

Schallenberger's parents, John and Laurie Sittley, could not be reached for comment, but local police acknowledged the heroism of the couple's decision to put the school's safety ahead of their family ties. Sam Parker, sheriff for Chesterfield County, said their decision saved lives.

"We all know that's a decision that would be very tough for any one of us to make as parents. We know they're heartbroken," he told ABC's "Good Morning America."

Family members turn loved ones over to the police all the time and for a variety of reasons, according Ann Adalist-Estrin, director of the National Resource Center on Children and Families of the Incarcerated, an advocacy group. Sometimes they go to authorities to protect innocent people they feel are threatened, sometimes to protect themselves, and sometimes to protect the very loved one who is to be arrested.

"Whenever a relative is in prison, family members feel guilt and a sense of responsibility even if they didn't personally turn that person in. Shame and stigma are the number one feeling for family members of arrested or incarcerated people," she said.

In Schallenberger's case, the alleged plan of attack was chilling. Police searching the family home found bomb-making materials, a pipe bomb and a detailed summary for a suicide attack.

"We applaud these parents and we're very thankful they chose to be concerned," Parker said. "They chose to get involved. We feel like they saved a lot of life in our county."

But saving the lives of others does not prevent family members from blame and second-guessing, sometimes suffering for years after their decisions put relatives in jail, or worse.

Others Have Turned in Relatives

Bill Babbitt knows something of that guilt, shame and stigma.

In 1980, he turned his younger brother over to police on a suspicion that he murdered a 78-year-old grandmother named Leah Schendel in Sacramento, Calif. Convicted of the murder and sentenced death, Manny Babbitt was executed in 1999, one day after his 50th birthday.

Manny Babbitt was wounded during the Vietnam War and had been awarded the Purple Heart. Bill Babbitt says his brother suffered from post-traumatic stress disorder and never recovered from the psychic wounds of war.

Bill was tipped off after finding a lighter with Schendel's initials on it.

"I went straight to the authorities. I thought about just buying him a bus ticket and sending him back to Rhode Island or Massachusetts, but I couldn't do it. I couldn't live knowing I had blood on my hands. I couldn't live knowing he might do something again," he said.

Babbitt says he was promised by police that if convicted, Manny would be placed in a mental hospital and not sentenced to death. Though he does not regret his decision to go to the police, he does regret not getting his brother help earlier when he realized he was mentally ill.

"At the time I didn't know about post-traumatic stress, but I knew he had a problem. I kept thinking maybe he'll find a job and start a family again. I wanted to be my brother's keeper. Once I realized he was unemployable, we had plans to take him the VA. But it I was too late. I should have done something; I should have got him help earlier."

"I carry a burden of guilt that I didn't act soon enough," he said.

Kaczynski's Brother Outs Unabomber

Perhaps the most high-profile case involving a suspicious family member alerting the police was the Unabomber killings.

Following nearly 20 years of mail bombs that resulted in three deaths, David Kaczynski told authorities in 1996 that he believed his estranged brother Ted was responsible.

"It is just a horrific dilemma. You want to protect people and protect your loved one, especially if your loved one has mental illness. I just knew my responsibility was to protect society at large."

"If we hadn't come forward and someone else was hurt it would have been impossible to live with the guilt. I had to deal with those voices in my head: 'This isn't my job. This is my brother.' As a family member I felt as if I was the only person close enough to know for sure, the only one close enough to stop it," Kaczynski told ABC News.com.

Schellenberger's parents also debated whether it was their job to go to the police, Parker told ABC News.

Parker said the Sittleys were initially worried that going to police would ruin their son's chances of going to college.

"They were very worried about his future and education," Parker said. "We said, 'We have to deal with his education or his life.' His mother told me at that time, it was a tough decision. We all know that it would be. She chose life over education, and again, we are very thankful for that decision."