OK, let's work backwards here:
1. High school students - unarmed and thanks in part to this guy - were not protected and then they were murdered.
2. The dirtbag in question already showed warning signs by doing something that showed contact or interest in some of those same innocent high school students.
3. All persons working at any school are guardians of those same kids in the place of their parents while they are in that school. Any warnings, any suspicions of those persons who may not be responsible in the very serious responsibility of protecting kids must be acted upon, immediately.
Any other response must mean that you aren't a parent.
And what does any of that have to do with he sexual harassment charge.