her brother-in-law, rodney. and he s a match. those prints belong to him. and they re in blood on lynn s arm. reporter: this is the smoking gun. it is. reporter: rodney was brought back to police headquarters by detective steve munoz. he was still a person, like, nothing fazed him. here i am. whatever you want from me, you want to talk to me, i ll give you whatever you need. reporter: when rodney sat down with detective chavarilla, he was confronted with the print evidence. and he denied everything. as we talked to him and broke down those denials, he became very emotional. rodney cried a bunch of times during the interview. and he revealed that he had, in fact, killed lynn. reporter: case closed? not even close. we had to answer the question of why did rodney kill her. why did rodney get involved in something so heinous and so horrible, so violent?