IF the grand jury finds evidence that it should go to trial then you will have the answer.
Where in the handbook does it state that the neighborhood watch folks are not to carry weapons?
Do you know if there was any interaction between the parties?
Zimmerman called police dispatch and when he lost sight of the suspect was returning to his vehicle where he allegedly was confronted by Martin from behind(?). Zimmerman broke off the "pursuit" as "requested" by the dispatcher. He was not "ordered" to stop.
If and when he is indicted, the jury selection may prove impossible to to complete because of the incorrect assertions that have been put out by the media.