Transcript for What Happened the Night Amanda Knox's Roommate Was Killed
When I first began covering this case, it almost seemed to be a tale of two amandas. Which was the real one? The innocent girl next door, out of her depth in a foreign country or foxy knoxy, of so many lurid headlines? Knox herself tried to set the record straight in her book called "Waiting to be heard" as she explained to my colleague, Diane sawyer. What's the first thing you want people to know about you? I want the truth to come out. I would like to be reconsidered as a person. Hey. It's Amanda Knox from west Seattle. Amanda Knox says imagine it was your daughter growing up in a middle-class suburb of Seattle. Her divorce add parents still living within walking distance of each other. Above all she says she loves her family. The wonderful thing about my family is that we need each other always, all of us. And whatever happens to one of us, happens to all R us all. She describes herself as quirky often too loud, unkrinserred, strange like the eccentric heroin of the French film "Emily" but she's still living in deadle in her senior year on the dean's list. When she decides she needed an adventure and venture out. An adventure of -- An adventure of self-hood. I was at an inge where you're innocent and confidence but at the same time -- Naive? I was naive enough that I didn't understand the way bad things can happen to regular people. For no reason. She worked three separate jobs to earn the money for her year abroad. Her steer, Deanna, dropping letter off at Italy, making a video as they head there, teasing her about her new life and the boys she'll meet. First up, the snanaked michelangelo stat ud of David. Statue of David. I don't know what it is about people that think guys are not attractive physically, but -- Though Amanda's real crush, harry potter. How do you like or in love with harry potter? I am. I'm Reading it in German. I'm going to get the second one in Italian. I'm not able to read it yet. I can't read Italian yet. It's going to happen, baby. You look at the person who arrived there, what do you want to say? I would tell her not to be afraid of what's going to happen. Because what happened to me hit -- hit me like a train. You are looking at a surveillance camera in perugia, Italy as day turns into night. November 1, 2007, 8:41 pm, there is a small dot there,hard to see, something moving. In court, they will say this is probably the last image of Meredith Kercher alive, heading toward her home about 100 feet away. She will be brutally attacked in her bedroom. And we warn you, this police video is graphic. There are 47 cuts and bruises on her neck, legs, face, inside her mouth. And around her body, etched in blood, a shoe print, a hand print on the wall, a footprint on the bathmat in the bathroom. Drops of blood on the faucet. Meredith Kercher had studied karate. It's clear she fought hard for her life, a life filled with possibilities. This is her acting in a music video back home in England. ♪ I'll be on my way ♪ she's studying politics in perugia, has lots of british friends. Then six weeks before her death, she meets her new roommate in the house, the American Amanda Knox. Knox says she and Meredith and their two Italian roommates became easy friends, happy. Though at the trial, Meredith's friends will testify she was annoyed by Amanda's loudness and lack of inhibition. Were you ever jealous of her? No. Were you ever angry at her? No. Amanda Knox has now been in Italy five weeks, going to school in the morning, working for a bar at night. Then she goes to a classical music concert and sees a young man who reminds her of harry potter. A graduate student in computer science. Nerdy, very inexperienced with girls, Raffaele sollecito says he can't believe the beautiful, uninhibited American is looking at him. Colpe de fumine. Colpe de fumine. That's a lightning strike. Yeah, he writes about how taken he was with me. And I really liked him, as well. They have known each other just seven days before they enter the 24 hours at the center of this mystery and this debate. The night of November 1st, when Meredith Kercher is murdered. Amanda Knox says she and her new boyfriend have been spending nights at his apartment. What are you doing the night of November 1st? November 1st we stayed in, and we had dinner. We watched a movie. His computer confirms that someone had ordered that movie, "Amelie." A witness confirms she and Raffaele were there in his apartment as late as 8:40 pm. We smoked. We had sex. We were together. We just hung out together. She says in the college town of perugia, marijuana was as common as pasta. And mostly it makes her goofy and sleepy. How high were you? I'd smoked a joint with Raffaele. And what that did to my memories was it made them less concrete. But it didn't black them out, and it didn't change them. You remember with clarity that you did not go out that night? You stayed in the whole night? We stayed in the whole night. The next morning, it is undisputed that Knox is the first person in the house where a murder has taken place. She says she made the five-minute walk from Raffaele's apartment home to take a shower and get fresh clothes. She says she noticed the front door standing open, thought it was odd, but the latch didn't always work. And even though she saw some blood on the sink, she says she took the shower thinking maybe Meredith hadn't cleaned up. Or was it her own newly pierced ears? At the sink when I was taking out my earrings that I noticed that there were speckles of blood. But speckles. A few drops. Did you see the bathmat? Did you see the -- Not yet, not yet. I saw that when I was getting out of the shower. And I thought it was strange. But you know people look at this and they say, door open, blood in the bathroom. Those are red alarms. Well, I had never before experienced anything in my life that was drastic. Because people think you'd be automatically concerned. Well, and indeed, I was. That's why I called my mom. She woke her mother in the middle of the night in Seattle. From this point on, Amanda Knox and her behavior will be a kind of kaleidoscope, shifting shapes, depending on what you see. Is inappropriate behavior evidence of guilt? Or as she says, was she just a tone deaf girl in a trauma? She sits on Raffaele's lap at the police station, playfully making faces. She tells Meredith's grieving friends that Meredith must have suffered, "She had her effing throat cut." Sorry about that now? I could have been more sensitive. Not knowing police are studying her every move. A female officer later testifies that Amanda Knox is doing cartwheels in the waiting area. She says she was just stretching after a long wait. As far as cartwheels or splits, I never did a cartwheel. I did do the splits. And then later on she claimed that I was doing a whole number of gymnastics, cartwheels, back walkovers. I did the splits. And that's once. But do you see how strange -- Well, what's strange is why these things got mischaracterized. I think everyone's reaction to something horrible is different. And perhaps most startling, this video, the first time much of the world will see Amanda Knox on newscasts. Knox seen here with her co-accused. She's outside the house where the body has been discovered. And people kept saying, where is the anguish? Where is what we think we would do if this happened to our friend? I have seen the same picture, like the kissing just can't stop. And that's not what that was. Kissing shown over and over again on the news. But when you look at the tape, there are three, quick kisses. And then, the rest of the time, she stares into space. She says thinking about how random fate, how she lived in that house, too. My friend had been murdered. And it could just have easily been me. Somehow she had died in the house where we were living. And it could have been me. But watching her, police are sure they have the killer. That American girl.
This transcript has been automatically generated and may not be 100% accurate.