Bullying is the use of force, threat, or coercion to abuse, intimidate, or aggressively dominate others. The behavior is often repeated and habitual. One essential prerequisite is the perception, by the bully or by others, of an imbalance of social or physical power, which distinguishes bullying from conflict.
Sounds to me like a person that is a bully can easily make the transition to becoming a stalker.
Below is a link to a resource that brings the dangers of bullying to the public’s attention. This is a good resource for your community. I’ve included a link to their bullying awareness and prevention guide:
http://www.learnpsychology.org/now/bullying/
Educating ourselves about these things really does help, not only in expanding our awareness, but gives us good lessons in our ever-evolving pursuit to keep our children safe in this society.