We might find out that he never had the chance, that Trashcan was on him so quickly and with no desire whatsoever to ask or answer any questions.
Notably, even though Zimmerman did not identify himself as Neighborhood Watch and was following Martin to some degree, that did not give Martin the right to attack Zimmerman. Martin, by throwing the first blows and putting his opponent in fear of his life, moved the transaction to the point that lethal force could be used against him.