While there's controversy about what happened the night George Zimmerman shot and killed Trayvon Martin, at least one thing is certain: which gun Zimmerman used. The Kel Tec PF 9 was the 9 mm with which Zimmerman fired the fatal shot.
Kel Tec is a gun manufacturer based in Cocoa, Florida. According to this review, the PF-9 was designed for civilian concealed carry permit holders. Most reviews mention it's small size and cheap price tag. One thing instructors tend to point out is that the PF-9 is only accurate at close ranges.
The gun does not have a traditional safety. It does however, have an extra strong trigger pull weight. That is why many gun instructors say it is OK to carry the PF-9 with a round in the chamber.
George Zimmerman had a round in the chamber the night he came across Trayvon Martin.