about to deliver an even more dramatic round how punch. >> we fraud isa took the stand as a prosecution witness. >> i asked him if he was responsible for her death, and he said yes. >> when you found out that information, what did you say to your brother? >> i told him -- bleep. >> why did you say that? >> because he took rosie's life. and i loved her. it just ruined his whole family. >> it was crippling testimony. once, an inseparable blood friend, hard given yards and evidentiary kills shot. nonetheless, there were still core problems in the prosecutions overall case. it was entirely circumstantial, and seemed to beg for a motive. why would the doctor do it? prosecutors answered by arguing that yaz the family man, wasn't really when you took a closer look. it turned out, he had a bunch