IMO it was likely Felipe Vidal who took the shot against Walker. Teenager told police a black car sped away which matched the description of the vehicle Vidal was driving at the time.
You're free to believe whatever.... But if you don't believe that Lee fired a bullet through Walker's window....Then how are you going to explain Marina ?? She knew all about the Walker incident and she actually believed Lee when he told her that he had tried to shoot Walker.... That's what he wanted her to believe, so if the police came looking for him while he was fleeing to Cuba she would tell them that Lee had told her that he had attempted to shoot Walker.