He bought those things at the store, but that doesn't mean he was holding them when he got shot.
From what I've heard, this whole thing sounds like a tragic misunderstanding, at least from Mr. Zimmerman's story: Mr. Martin thought he was being followed by a racist and attacked Mr. Zimmerman, and Mr. Zimmerman panicked and shot him. They both had reasons to fear for their lives.
Of course, that's just Mr. Zimmerman's story. If The prosecution's story is correct, that's different.
But I haven't heard anything on this in months until now.