Why was he acquitted? He had a great lawyer. The lawyer repeatedly challenged the circumstantial portion of the government’s case and the reliability of the scientific evidence related to testing of gunshot residue and cell tower tracking of Zimmerman’s car. All this according to the Herald & Review. See full article:

https://herald-review.com/news/state-and-regional/crime-and-courts/not-guilty-mclean-county-jury-acquits-kirk-zimmerman-of-killing/article_153d7116-a7ec-55fe-8d42-5c38fe69359b.html