After the Columbine High School massacre of 1999, the Secret Service pored over decades of law enforcement and school records in an attempt to gain a greater understanding of students who kill.

Nearly six years later, in the aftermath of a teenager's shooting spree on a reservation in Minnesota this week that killed nine people and wounded seven, authorities have yet to pinpoint why school shootings occur. Nor have they succeeded in developing even a reliable profile.

But law enforcers, school officials and mental health professionals agree on a few things: School shooting incidents are not concocted in a vacuum. Often times, the perpetrators telegraph their intentions by telling friends or expressing dark images in their artwork, writing or manner of dress. According to a Minneapolis-St. Paul Star Tribune report, Red Lake (Minn.) High School shooter Jeff Weise once told friends, "That would be cool if I shot up the school." His friends dismissed it as talk.

Therein lies the problem. It's impossible for peers, educators and even family members to discern "talk" from legitimate threat. Such statements require further examination by professionals such as those in law enforcement and mental health who are trained to assess threats. Even then, there are no guarantees.

But telling law enforcement and school officials about a student's threats or odd behavior gives them an opportunity to intervene before a tragedy occurs. In Vernal, a parent's telephone call to police regarding a child who didn't return home as scheduled tipped police to an alleged plot to bomb Uintah High School late last year. The teens' defense attorneys contend that the accusations have been overblown.

In the post-Columbine world, schools must create climates in which students are comfortable reporting bullies, threats or other unusual behavior. That's easier said than done, since students abhor tattling on one another. But the Red Lake case demonstrates — once again — that students have to take action to protect themselves and school personnel from students who are bent on harm. School administrators have a responsibility to further investigate the concerns.

Parents must do their part to curb school violence. Plainly speaking, that means parents owe it to their children and their communities to be actively involved in parenting. An FBI study of 18 school shootings determined that school shooters share six family attributes: a turbulent parent-child relationship; the parents' acceptance of pathological behavior; lack of intimacy; no limits or monitoring of TV or Internet use; access to weapons; and a dominance in the household. In other words, kids need limits and nurturing, which sounds simple enough but becomes more difficult as children age and become increasingly independent.