then they asked her if diana had said anything about peggy nadell's murder. answer blew them away. >> she did say that she was there at the mother-in-law's. >> did she tell you who stabbed her? >> no. >> reporter: prosecutor richard moran was there listening in another room. >> and that's the first time we have first-hand information that diana was in the house. >> reporter: before long, diana was in that same miami interrogation room where she recognized some familiar faces she probably wasn't pleased to see. >> you know who we are, right? >> yeah, why wouldn't i know who you are? >> okay. just making sure. >> steve and earl. >> reporter: and she knew why they were there. >> you think i killed my mother-in-law. is that what you're telling me? >> reporter: yes, it was, and after five months, their investigation was about to end. >> you're under arrest for the murder of peggy nadell. >> i did not murder my mother-in-law. >> reporter: that same day, another team arrested andrea benson in d.c. detectives lorence and cole-hatchard were confident they had the righ