Trayvon probably was a budding burglar, but there’s no real evidence he was involved in criminal activity on the night he died, prior to the altercation with Zimmerman.
Although he may very well have been casing houses, as Zimmerman suspected, there isn’t really any evidence of that.
He attacked Mr. Zimmerman, so whether or not he was out in the rain casing houses is here nor there. The state’s “star witness” Rachel Jeantel admitted as much.
Zimmerman did not shoot Trayvon for casing homes. He shot him in self defense when Trayvon attacked him and then went for Zimmerman’s gun.