wouldn't you know, robert denney's dna was a match.her kitchen sink. all of the other possible suspects, the next door neighbor, the dishwater, and tiffany were cleared in the case. >> we were jumping up and down. >> we wanted to go get him. then >> prosecutor angela cori said no. >> he could come up with a story to explain that dni away. i carried her grocery is in for her, i cut my finger. you cannot give anybody a chance to explain it away. >> the prosecutor wanted him on the record, denying that he had ever set foot in the victims apartment. then they would hit him with the dna proof, trapping him. so they sent katie kingston back up to marilyn, to robert denney's house. >> i was going to play like i did not know anything. >> you are acting. >> just acting down. >> they told denney that they had found the man who killed his old neighbor corey parker. the detective was just here to tie up loose ends. he seemed willing to help, but what he didn't know is that the detectives was wearing a wire. >> do you know corey? >> no. >> okay. no