Sam assumes that he is there to prevent Lisa from ruining her career, and discourages her from telling anyone about the alibi, figuring that since he is only a minor suspect, he will find some other way to prove his innocence.
He is there to prevent Lisa from ruining her career, figuring that since he is only a minor suspect, he will find some other way to prove his innocence. This is what Sam assumes. Sam discourages her from. Sam is telling anyone about the alibi. He will find some other way. This is to prove his innocence. He is only a minor suspect. Sam is figuring this.