Here are the facts about GZ:
He called the cops to report suspicious individual. He described the individual as looking up to no good because it was in a close knit gated community, TM wasn't recognizable to GZ, the community had a rash of break ins and TM was casually walking in poor weather conditions.
When asked to come into the police station GZ went willingly without legal counsel and was eager to talk about it. (A sign of telling the truth because liars try to avoid talking about their lie). When asked to take a lie detector without legal counsel he again wanted to. The lie detector determined he was telling the truth. As for variations in story, again, a sign of telling the truth. The same story usually means its scripted or practiced. Humans recollect different things and different times and that's one reason stories change over time. Even when telling the truth.
Within trial multiple eye witnesses corroborated GZ story. Again, a sign he was telling the truth.
But for some reason, media got wind of this, said GZ racially profiled, edited the police call and made said he made racist remarks (which are lies. GZ was suing the news for slander as he should).