"if someone follows a suspicious looking (and acting) person in his crime-ridden neighborhood"
That's Zimmerman's discription.
Trayvon went to the store, bought a drink & candy, was talking to his girlfriend and returning home to watch the rest of the basketball game.
That is not 'suspicious looking', unless you're looking for trouble & packing a gun & acting like a vigilante.
And Zimmerman has a history...

DO SOMETHING!