Produced by Doug Longhini, Clare Friedland, Paul LaRosa, Sara Ely Hulse
The welcome home signs in Seattle say it all.
"My family is the most important thing for me right now and I just want to go be with them," Amanda Knox told supporters at a welcome home press conference in her hometown.
Amanda Knox is doing just that -- reconnecting with family, friends and adjusting to freedom.
"We've now kind of woken up and realized that the nightmare is over," Amanda's father, Curt Knox, told "48 Hours Mystery" correspondent Peter Van Sant. "Living for four years inside a concrete and steel prison and now being able to kind of look around, smell the air...it makes a huge difference."
It's almost hard to believe that days earlier, her face was filled with fear as Amanda Knox stood up in court -- with the whole world watching -- to deliver the most important speech of her young life.
In fluent Italian, she spoke forcefully and emotionally, proclaiming her innocence in the murder of her roommate, Meredith Kercher.
"I am not what they say..." she told the court." "...the perversion, the violence, the disrespect for life, for people, that's not who I am. ...I did not do what they claim I did. I did not kill, rape, I did not steal. I wasn't there. I wasn't present at this crime."
More than 10 hours later, the tension was almost unbearable. A judge read the verdict: Not guilty. Amanda was quickly rushed from the courtroom.
It was the end of a long and difficult road for her family.
"I watched Amanda and I saw her slump, and I went 'No' and then our attorney that speaks English turned around and said, 'She's free,' and [I] couldn't tell you, couldn't' be better," said Curt Knox.
Amanda's family had sacrificed everything to be near her, and so did one very determined best friend, 24-year-old Madison Paxton.
Paxton moved to Perugia in 2010, and played a crucial, behind-the-scenes role as morale booster and confidant as Amanda prepared for her new trial.
"Your spunkiness and the nature of your relationship with Amanda, you've really encouraged her to stand up and fight," 48 Hours correspondent Peter Van Sant remarked to Paxton.
"Very much so," she replied. "I can remind her ... that you can be mad, that you should be mad, and that it's fine for you to defend yourself."
Just about every Tuesday and Saturday, for the past 10 months, Madison took a 15-minute bus ride and then set out on a 20-minute walk, to see her best friend in prison. Her visits provided much-needed human contact during times of desolation and despair.
"I remember one time when I visited her, and she just had an eyelash. And so of course I brushed it off.... And the letter I got from her a few days later, she wrote ... how much it meant to her that I brushed off her eyelash, just because it's like a kind, friendly, physical gesture and that just doesn't exist for her anymore."
Paxton kept a video diary at "48 Hours"' request. The powerful entries provide an inside look at what Amanda was thinking and feeling while trapped behind bars.
Paxton video diary excerpt:
"She's beyond heartbroken. She is depressed. She's absolutely terrified...
"And Amanda, she's just like, 'Why do people feel that they have a right to like, make these presentations about my life when I've never met them and they don't know me?' And I just turned to her and I was like, 'Babe, cause you're a character to them; you're not a person, you're a character.'"
How could all this have happened? "48 Hours"' investigation reveals an incredible story of how police and a powerful prosecutor twisted the evidence to fit their theory of the crime.
It started on Nov. 2, 2007, with the murder of her 21-year-old British roommate.
TV Reporter: Police say Meredith Kercher was found partially clothed and had been left in a pool of blood with a deep cut to her throat.
Amanda had no idea how quickly she would turn from witness to suspect. Her troubles began with a kiss with Sollecito that would be played over and over again on Italian TV.
"And from right at the beginning with those series of kisses, Amanda Knox was demonized in the Italian mind?" Van Sant asked Bob Graham, an investigative journalist and CBS News consultant.
"Yes. It showed a callousness; it showed a disregard for this moment when her flat mate had been murdered," he replied.
And if Amanda could be so cold, Prosecutor Giuliano Mignini thought, that meant she could also be involved. Amanda's mother, Edda Mellas, had a very different view.
"It's not passionate kissing. It's comforting and consoling behavior ... because she was devastated," she said. "...you can tell she's in shock."
Ironically, Amanda's eagerness to stay in Perugia and help the police was backfiring on her.
"She had the opportunity, on several occasions, to leave the country," according to Graham. "Her aunt in Germany phoned and said, 'Amanda, your mum says you should get out of the country.' ...and she said, 'No I want to stay here. I wanna help solve my flat mate's murder.'"
Amanda was interrogated for a total of 50 hours, over four days, without an attorney. None of the questioning was recorded.
"And these are people who are trained to break Mafia suspects," Van Sant noted to Paxton. "Yeah, they break Mafia," she replied. "And here, they had a little 20-year-old yoga hippy from Seattle who thought that everybody was wonderful and just wanted to go have coffee together."
The brutal interrogation ended with Amanda confessing -- putting herself at the scene and implicating another person, her boss at a local bar where she worked, named Patrick Lumumba.
Author Nina Burleigh has been studying the case.
"She's signed a statement that says, 'I see myself in the house... Patrick with with me -- Patrick Lumumba. He's gone into Meredith's bedroom. And I can hear her screams,'" said Burleigh.
The statement Amanda signed implicated Lamumba with a bizarre and awkward line: "I confusedly remember that he killed her."
"I take offense with the word confession cause Amanda never says that she participated in the murder of her friend ... she never confesses to being part of that crime, ever," said Mellas.
There were many troubling details about that so-called confession. But it was all the police chief of Perugia needed to arrest Amanda, Raffaele Sollecito and Patrick Lumumba for the murder of Meredith Kercher.
"He had the nerve to say case closed, we've solved this murder," Graham said. "That's OK if you've got the evidence."
In fact, none of the forensic evidence -- including the DNA testing -- had even come back. But the prosecutor insisted his gut -- and Meredith's near-naked body -- told him how the murder had occurred: During a drug-fueled orgy. And Amanda was the ringleader.
"Amanda was presented ... as extremely attractive, having lots of sex, decided one night to act on these completely diabolical urges and bewitched two men into attacking her roommate," said Burleigh.
And the world's media ate it up.
Asked if Amanda's beauty played a role in all of this, Paxton told Van Sant, "...it definitely sells more papers if you have two beautiful, beautiful women and then headlines that there was some attempt at an orgy between them."
To prosecutor Mignini -- an orgy that led to a satanic killing.