Do we know if Trayvon was tested for that in his system?
I don't know. I do know it is not like the movies of TV where they easily find whatever substance helps the plot that they didn't even think to look for! :-) From my very limited understanding, I think coroners have to purposely look for whatever substance they pre-determine to test for. If a substance isn't searched for specifically, I don't think it shows up on some test. Thus, if they are looking for substance "A" but only substance "B" is in the body, they don't find "A" or "B." THC was in his system. Other than that, I don't know.