assistant d.a. moran didn t think so. peggy would never have let a stranger like andrea benson into her house. so that had to be a friendly voice on the phone? yes. reporter: detectives thought that voice might have belonged to diana, but they had nothing to put her on the scene, in peggy s house. at this point, is susanne off the hook? diana is now the higher suspect. susanne wasn t off the hook. reporter: they could be in this together? correct. yes. that s where it was. reporter: because they both benefited. absolutely. yes. reporter: now eight weeks into the investigation detectives still didn t know who had killed peggy nadell. with suspects in florida, d.c., and new york, detectives came up with a new strategy. and their phone expert liked it a lot. gutsy. like, i mean, a lot of people don t go to those lengths on a homicide case. i thought it was a brilliant strategy.
woman was lying, and that diana was trying to cover her tracks. but they still didn t have enough to charge diana. so they headed to miami, to speak with diana s friend who bought that tracfone, karen hamm-samuel. they brought karen into miami police headquarters for questioning. all set? reporter: karen admitted she bought that tracfone for diana. then they asked her if diana had said anything about peggy nadell s murder. her 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