why would steven avery do this? >> that's a good question. >> reporter: we asked ken katz, who has written a book that revealed his provocative theory that steven avery made himself a murderer. >> he started planning this event the first day he went to prison. >> reporter: and we talked with tom fassbender, a lead investigator in this case, who has come under fire for this silent interrogation. you have stayed silent through the firestorm. why are you sitting here today? >> i finally realized that someone needed to speak out and tell the truth of what happened here. >> reporter: so, what did happen here? the story begins with the woman at the heart of this case, a 25-year-old photographer from wisconsin named teresa halbach. >> she just loved being behind the camera. >> kim peterson and teresa became friends in college. they both worked at the same studio in green bay and she said teresa had a special way with the subjects. >> she could make them smile. i think that's what she loved to do. >> reporter: the two staye

>> how do you feel that so many people think that steven avery is innocent? >> it's emotional. they made him look like he was a nice person. what's happening is wrong. >> the evidence is beyond overwhelming. steven avery is guilty. >> i'm innocent. >> the story gripped the nation, in the series, "making a murderer." >> so many americans have learned about it. >> it's being heard around the world. >> steven avery and his nephew convicted of murder in the killing of a young photographer. but were they really innocent? >> i didn't do it. somebody's doing a good job against me. >> did you have a vendetta against steven avery? >> absolutely not. >> for the first time on television a lead investigator defends his interrogation which led to the conviction overturned. >> this was seen by many as a false confession. al. >> i feel it was a real confession. >> we need you to be honest with us. >> right from wrong. >> those officers wanted that information in the worst way. and they got it in the worst

." >> how do you feel that so many people think that steven avery is innocent? >> it's emotional. look like he was a nice person. what's happening is wrong. >> the evidence is beyond overwhelming. steven avery is guilty. >> i'm innocent. >> the story gripped the nation, in the series, "making a murderer." >> so many americans have learned about it. >> it's being heard around the world. >> steven avery and his nephew convicted of murder in the