And an eyewitness clearly stated that Martin was on top of Zimmerman beating the crap out of him. Doesn't sound like he was too scared. Following someone who has aroused your suspicion is not "stalking", which would be defined by persistence. Since this incident occurred in the course of one day, "stalking" does not apply. I suspect Zimmerman was arrested to protect him from the repeated open threats of violence against him. Now that's "stalking", with no hint of prosecution.