Message Is Clear in N.Va.: IM 'Threats' Can Bring Teens Trouble in an Instant

"They, like, talked to me and said, 'If you ever get a strange message, tell us,' " she said. But in light of what happened at Yorktown, she added, "I think I would try to figure it out first on my own."

That is what some adults fear.

Katherine S. Newman, a sociology professor at Princeton University and the author of "Rampage: The Social Roots of School Shootings," said the recipients and the two schools were right to take the threats seriously in the wake of deadly incidents such as those at Columbine High School in Colorado and Red Lake High School in Minnesota.

"You did get some ridiculous things [after Columbine], like a kindergartner being expelled for pointing a chicken finger at someone and saying, 'Bang, bang,' " she said.

But, she noted, "if ever they ignored a threat that was credible and something happened, the community would go up in flames."

Still, Newman said "zero tolerance" policies for verbal threats and punishments that students perceive as too harsh could lead some to hold back crucial information.

In every violent school incident she has studied, she said, there were students who had heard something was going to happen. But Newman said students often won't cross the line between adults and youths because they fear being seen as a traitor.

"They'll say to themselves, 'If I tell, Johnny's going to be thrown in jail for three weeks, and do I want to be the one to tell and be fingered as the one who told?' " she said. "And then we lose the most important and accurate information we have."

Staff writer Jamie Stockwell contributed to this report.