Last week's all-too familiar workplace massacre in Illinois has prompted more media soulsearching about how to spot a dysfunctional work-mate who is likely to blow you away.
Police report that in three cases last month heightened awareness in schools and an unexpected willingness to blow the whistle on schoolmates have almost certainly averted three tragedies similar to the devastation caused at Columbine High School in Colorado two years ago.
Only 60 miles away from Columbine, in Fort Collins, two teenage girls had listened for several weeks, in the lunchroom or school hallways, to two classmates talking about how they planned to restage the Columbine massacre on its second anniversary in April. They spoke of guns and a propane gas tank which would serve as a bomb, and how they could seal off the exits of the school.
On a visit to one of the young men's homes, he even held a gun to the head of one of the girls.
Despite a strong attachment to the boys, the girls told the police. And, while their lawyers now deny that the boys really intended to carry out a massacre, the young women have little doubt they did the right thing in revealing the alleged plot.
In Hoyt, Kansas, following an anonymous tip-off on a hotline installed in the school following a number of school killings in 1997, police recently arrested three students.
They were found to be in possession of an AK47, some bomb-making equipment and a plan of the school indicating where explosives could be planted. They also had white supremacist and racist drawings.
The tip-off appears to be a strong vindication of the policy of the local schools who eschewed increased security, metal detectors and armed guards in favour of a consciousness-raising exercise among parents and students.
"We don't want our schools to be armed camps," the school district supervisor, Ms Marcetta Reilly, said.
In another case the vigilance of a student doing part-time work processing films in a California drugstore appears to have saved the day.
Ms Kelly Bennett, a first-year student in San Jose State University, was disturbed by photographs of 19-year-old Al Joseph DeGuzman with an armoury of guns and pipe bombs.
She too rang the police and engaged DeGuzman, a student at De Anza Community College, Cupertino, in conversation long enough for them to arrive and arrest him.
At his home they found four rifles, 30 pipe bombs, 20 Molotov cocktails, 2,000 rounds of ammunition, and a tape recounting his obsession with Columbine. Police say he had planned to go on the rampage in his school cafeteria the next day. His lawyers say he simply has "an innocent fascination" with weapons.
At De Anza, students posted a large banner thanking Ms Bennett, and the school has opened a scholarship fund for her.
Experts say that developing such a whistle-blowing culture among teenagers is crucial to stopping future massacres. They cite research which shows that in three-quarters of the 37 school gun attacks since 1974, the assailants told someone in advance about their intentions, usually a fellow student.
