Just when are authorities allowed to step in and try to prevent someone who might generate the kind of 33-fatality massacre that occurred on the Virginia Tech campus last week? Whose rights are violated when someone who poses a danger to others is arrested or put under surveillance so he or she cannot pursue their deadly plans?

The gunman blamed for the Blacksburg tragedy, the deadliest shooting in U.S. history, was accused of stalking two female students at Virginia Tech and had been committed to a mental health facility in 2005. An acquaintance was concerned that Cho Seung-Hui might be suicidal, according to police.

Cho pestered one woman so much in 2005 with telephone calls and e-mails that police were notified. The woman declined to press charges. Neither of the women he harassed was among the Virginia Tech victims.

Time after time, people, including fellow students and faculty people, saw signs of a troubled existence that might trigger something tragic. The man was a loner who seldom communicated and often wrote disturbing works of fiction. People tended to give him a wide berth because of his grim idiosyncrasies. His bizarre behavior had become even more obvious in recent times and he had become even more reclusive. He didn’t reach out, seldom talked and one fellow student said, “We just really knew him as the question-mark kid.”

Where can authorities in education and law enforcement draw the line? Consider young people in high schools who have caused death, injury and damage via well-planned assaults. Some were never headed off; others who have been found plotting violence have been “schooled” and allegedly rehabilitated and, to date, have not regressed. Yet even when young people are found to be ready to commit mayhem, they too often are coddled and not taken as seriously and penalized as harshly as they should be.

Cho is of Asian heritage. Had he been taken in and questioned and prevented from carrying out his massacre, would there have been a hue and cry about “racial profiling” and invasions of rights? We have so many people who are critical of what Virginia Tech and the law enforcement people did NOT do in this matter. Yet our system of presumed innocence sometimes can hamper prevention and heightens the chances for reparation after a terrible deed is done. At what point can we as citizens and as Americans step in and take the steps to derail a murderous express like Cho Seung-Hui without being charged with human rights violations?

The answer is that there is no answer, no matter how much we theorize. We as Americans have to be cautious but we also live on trust and the belief that most people are good and mean no harm. Clearly that has grisly exceptions and, as things stand, there seems little we can do to plug the leaks before a dam of hate and emotion breaks.