who liked circumstantial cases, john lewin.riminal case. it was also the very last one of detective jim wallace's long career. he'd be testifying from retirement as a private citizen, a cop no longer. >> good morning. >> reporter: and so they all assembled. in the very courtroom where robert shapiro helped acquit o.j. simpson. and sitting in the gallery, what was left of lynne knight's family, though donna's mother, dead almost nine years, was certain on donna's mind. >> towards the end, we had a lot of mother-daughter talks. and she grabbed my hand. and she goes, "you got him, kid. i know you got him." and so my mom died knowing. she knew. she knew. >> reporter: here, for the very first time, lynne's family got a look at the man accused of killing her. the man once invited to donna's wedding. >> i really felt i was able to look him in the eye and say a lot of things in my head that he wasn't hearing and that weren't polite. >> reporter: prosecutor john lewin would have to sell what was, perhaps, the most completely circumstant