Transcript for Why Oscar Pistorius' Ex-Girlfriend Was Afraid of Him
Good evening. Tonight, you'll see our confrontation at the auto shop and at the cosmetics counter. Looking out for you. But first, what was it like to live with Oscar Pistorius, at home tonight, guilty of manslaughter. Another longtime girlfriend before reeva steenkamp, confe confessing how scared she was. Shot his girlfriend. Girlfriend. Reporter: When news broke that Oscar Pistorius had shot to death a woman in his house, many people assumed it was another blond beauty, Samantha Taylor. People thought it was you. People thought it was me. I received a lot of, you know, rest in peace messages. That was really scary. Reporter: Scary because Samantha had been Pistorius' long time girlfriend. Just 17 when a 24-year-old Pistorius swept her off her feet. He was already a worldwide celebrity. Their first date a month after his historic run as the first amputee to compete against able-bodied athletes in a world championship. Samantha and I met outside capetown, the majestic Seaside city where she now lives. We had a great time together. He was very charming. He is a really good guy, you know, he was very respectful -- very kind. Reporter: Samantha's mother Trish eagerly welcomed the sports hero into their close knit family. How well would you say you knew Oscar Pistorius? Very well. Reporter: She says she soon took on an unexpected maternal role, offering him advice and support. He spent a lot of time at our house. I think in the beginning I saw what he wanted me to see. And then, as time went by I think I started seeing a very different person. Reporter: Trish says she quickly discovered a dark side his adoring fans never saw -- what she calls a "Lost and lonely soul." Sometimes exploding with fits of anger. I heard him screaming at Samantha once on the phone, yelling. Reporter: Through the phone? Yeah, through the phone with foul language. That shocked me. Reporter: Were you ever frightened of his temper? Oh, yeah, definitely. Reporter: You say he would shout at you. For what? I didn't take my plate to the kitchen. Reporter: He would shout at you for not taking your plate to the kitchen? Yeah. Reporter: She said life with the "Blade runner" was like living on a razor's edge. So, did he drive fast all the time? Yeah. Pistorius had a love of danger and a need for speed. He drove in the car with you at 200 miles an hour on a busy highway. If anything happens, you both are dead. Yeah. Reporter: How close do you think you came to death with Oscar? There were a couple times that were quite close. Reporter: For Pistorius, she says, there were no limits. Not just with cars but with his everpresent guns. He definitely had a passion for guns. Did he always carry it with him? Yes. Reporter: He didn't just carry it. He used it. Samantha was in the back seat of a car with Pistorius and a friend when pistorus fired his gun. He shot out the roof of the -- So, before you knew it he suddenly shot out into the roof? Yeah. How loud was it in the car? It was really loud. I got such a fright. I think Oscar was an accident waiting to happen. Reporter: That is the title of the book Melinda Ferguson has co-written with Trish Taylor detailing Samantha's 18-month relationship with Pistorius. He was the bullet in the chamber. The Nike ad. The guy who was always -- something was gonna happen. In a sense, it was all leading up to some tragedy. Reporter: That's because Samantha and her mother say Pistorius was deeply unstable, not the confident champion everyone else saw but an emotional wreck. The man some thought turned on the tears for courtroom theatrics, according to Samantha, was truly a constant crier. How many times have you heard him cry? A lot. Ten? 20? 50? Probably about, maybe 300? You're not exaggerating? No. Reporter: The olympics, she says, was his lowest point. The man who proudly held his country's flag at the paralympics was cracking under the pressure, barely keeping a grip. He was crying to me on the phone every day. Just saying how he was lonely and he didn't know what to do with his life. He was very isolated. I thought, "What if he commits suicide?" I was getting really, really worried about him. He had made all these promises on how he's gonna see a psychologist, how he was gonna change his life and everything was gonna change. Reporter: But nothing did change, Samantha says. And worst of all, she says he was cheating on her. You know, there were definitely a lot of other women in his life at the same time as me. Reporter: In a lengthy e-mail addressed to Trish and Samantha during his olympic training, Pistorius wrote, "There are often very dark areas that haunt you. Most of my adult life I have had moments that I sabotage the good that I have." "Sometimes I find it easier to believe that there is darkness in others like I know it is in me." He writes a lot about his darkness. A lot. Reporter: Then, the final straw. Samantha claims they had not officially broken up when Oscar shows up on television at an awards ceremony with another blonde, the woman who would die at his hand, reeva steenkamp. I went downstairs and the awards were on and Oscar had reeva on his arm. And Sam was watching it? Yeah. And I just thought, "What a bas St. Ard. Reporter: Oscar testified that they were no longer a couple when he was with reeva and that he never cheated on her. But all agree that after that outing, their relationship was over. Their next meeting would be in court. Oscar got very angry. Reporter: The last person Pistorius may have wanted to see there, his ex. You said Oscar screamed at you. Yes. Reporter: As for Pistorius' testimony, Samantha has intimate knowledge that gave her pause. You shared a bed with Oscar. Yeah. Like reeva. The same bed, in the same room. Uh-huh. Reporter: She says parts of his story, that he believed reeva was an intruder, did not ring true. There were things that didn't match up to my experience staying at his house. Reporter: "Things" like Pistorius claiming he didn't see reeva walk to the bathroom. I didn't see her getting out of bed. It was pitch black. Reporter: And Samantha says Pistorius did not typically keep his room that dark. Did he sleep with the curtains closed? He usually slept with the curtains fairly open. He always had some light coming in. Reporter: Samantha said that although Pistorius did startle easily, he would always ask her about any sudden noises. If there was a noise we discussed, "Did you hear that?" Reporter: When you heard that Oscar didn't really make physical contact with reeva that night, did you find that odd? I -- I did. I found that very odd. Reporter: Pistorius' spokesperson declined to comment for this story. The judge ultimately ruling that Pistorius shot reeva unintentionally. And today convicted him of manslaughter. He is found guilty of culpable homicide. Reporter: Just this morning Samantha told me, "No one besides Oscar knows what happened on the morning of reeva's death, but having said that we all need to move forward with our lives." Do you still love him? I think a part of you will always have love for someone that you've loved. But I think that -- you know, that was a chapter in my life, and that chapter's closed. A chapper closed, but Pistorius' is still open.
This transcript has been automatically generated and may not be 100% accurate.