Take Note: Detection or deception?

The name sounds like something out of "Star Trek,'' and the device appeared to be a blessing to educators seeking safer schools.

The Quadro Tracker has been marketed as a "positive molecular locater," a hand-held device that can detect weapons, explosives, or drugs.

The Quadro Corp. of Harleyville, S.C., has marketed the gizmo to law-enforcement agencies, correctional institutions, and schools. More than a few school districts, eager to do something to make their campuses free of weapons and illegal drugs, apparently have forked over $995 for what its manufacturer calls the "school version"...