Are the results of a search of my car due to a trespassing charge null and void if I’m found not guilty of trespassing?
First, from the facts, it does not appear that you were tresspassing.  That said, unless they had a warrant, the search of your vehicle is presumed unlawful.  The remedy for an unlawful search is suppression of the evidence found in the vehicle.However, you or your attorney are going to have to file a motion to suppress the evidence. The basis for the warrant would be that the police officers did not have reasonable suspicion and/or probable cause to search your vehicle. Wherefore, all evidence seized do to te unlawful search should be suppressed.Hope this helps.