reporter: by the young men themselves. they weren t real. wax. reporter: the real-life details of the defense that shocked america. uhm, we would be in the bathroom, and uh, it would, he would put me on my knees. i m lookin to see, is he tellin the truth or not? reporter: tonight, we ll ask the brother at the center of it all about truth. to this day i m still dealing with with the controversy of it, obviously, my own guilt in what in in what happened. reporter: what really happened and why. so to understand, where to begin? how about here illinois. the 1940 s. everybody who knows this story knows her as kitty. but that wasn t really her name, was it? no. it was mary louise. reporter: she was the baby of the family, said her older sister joan vandermolen. it was one of their brothers who came up with the nickname that stuck for life.
and what the brothers did after the murders shocked the whole country. they were just spending, spending, spending. reporter: three rolex watches. a private tennis coach for erik a porsche lyle even bought a chicken wings restaurant. i love to shop. but i think that i might even wait a day or two. reporter: lyle went to visit his cousin alan in chicago after the murders. he ordered some of the most expensive shirts i ve ever seen in my life. he ordered some jewelry, ordered these shoes these expensive shoes. and i was like, wow. the way he was spending money, for me, was very strange. reporter: but to other relatives, the spending was just lyle and erik doing what they always did. lyle was grieving , said cousin diane. people would ask, you know? people were like, what s he doing? and i would defend him and say, well, everybody reacts differently when somebody dies. this is just his way of coping i guess.
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anymore. and he burst in tears and left. well, lyle and dr. oziel, more or less, followed him. and lyle got to the elevator. and dr. oziel said, am i in danger? and lyle said, that s all i can tell you is have a good life, dr. oziel. and it freaked him out. reporter: what followed was a strange and nervous dance, oziel told lyle and erik to come back for follow up therapy sessions. the brothers, afraid oziel might go to police, agreed. during one of those sessions, they both confessed to killing their parents. and oziel recorded the conversation. judalon smyth learned about the recording and told detectives, who promptly seized the tape. just one problem, they weren t allowed to listen to it because of doctor/patient privilege.
cuba a territory of the united states. reporter: now, with his father s death, erik said he and his brother wanted to fulfill his father s dream. i wanna become senator of florida and my my brother wants to become president of the united states. reporter: then the mood shifted and erik described what he saw when he walked into the family den on august 20th. they weren t real. no. they wax they looked like wax. it s something that i ve never seen my dad helpless. you know, i think that possibly if lyle and i would ve been home, if we would ve been able to do something about it maybe uh, maybe my dad would be alive. i definitely would give my life for my dad s. reporter: and, this was curious, erik also told rand about a screenplay he had written called friends. that story was about a young man who murders his parents and inherits $157 million. reporter: fancy that.