I thought I heard discussions earlier on tv where supposed experts didn't think they'd be able to use this evidence. However, he also, as I understand, hid the fact that he had two passports.
Since Treyvon isn't able to speak for himself it's basically Zimmerman's account so it would seem his credibility should matter.
TIS
"Mankind must put an end to war before war puts an end to mankind. War will exist until that distant day when the conscientious objector enjoys the same reputation and prestige that the warrior does today." JFK
However, he also, as I understand, hid the fact that he had two passports. 
