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Anderson Cooper 360 Degrees

Murder Abroad: The Amanda Knox Story

Aired March 29, 2013 - 22:00   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

ANDERSON COOPER, CNN ANCHOR: Her face and name were everywhere. Italian media portrayed her as an exchange student gone wild.

Amanda Knox, authorities there said, belonged in prison for a long, long time. And they sent her there on iffy evidence and shaky testimony that would later crumble.

So, after four years in prison, Amanda Knox went free, came home, spent a year-and-a-half putting it behind her, or at least trying to. But now she's learning from Italy's Supreme Court that the verdict that freed her wasn't the last word.

Drew Griffin now on how her nightmare continues and how it all began.

(BEGIN VIDEOTAPE)

DREW GRIFFIN, CNN INVESTIGATIVE CORRESPONDENT (voice-over): In Italy, a British exchange student raped and murdered in her room.

UNIDENTIFIED MALE: It was horrible. The young lady bled to death.

GRIFFIN: Amanda Knox, her American roommate, charged with the crime.

UNIDENTIFIED FEMALE: My husband called me and said they have arrested Amanda.

EDDA MELLAS, MOTHER OF AMANDA KNOX: My husband called me and said they've arrested Amanda.

GRIFFIN: A media frenzy rife with tales of cover-up and sex games turned deadly all centered around the beautiful young student dubbed "Foxy Knoxy" by the tabloids.

Convicted of murder, then freed after spending four years in prison, when her conviction was overturned. Now in a seemingly never- ending turn of events, Amanda faces trial again for the murder of Meredith Kercher in what has become another haunting chapter of murder abroad.

Amanda Knox was going into her junior year of college. Her mother Edda recalls Amanda the fresh-faced 20-year-old intent on adventure.

MELLAS: She was going to study abroad going into college somewhere. She didn't know where yet.

GRIFFIN: Amanda would decide on Perugia, Italy. Her sister Deanna remembers when she moved into this house which she shared with three other girls, two Italians and one British student named Meredith Kercher.

(on camera): Why was she so set on that apartment?

DEANNA KNOX, AMANDA KNOX'S SISTER: I think it's because of the people really. It was close to the college and her roommates are the sweetest people in the world.

GRIFFIN (voice-over): But after only six weeks in Italy, on the night of November 1, 2007, Amanda's overseas adventure would take a bizarre turn. Amanda claims she slept over with her boyfriend, Raffaele Sollecito, that night. According to her, they cooked dinner at his house, smoked hashish and made love.

On that same night, Meredith Kercher returned to the home she shared with Amanda after watching a movie with friends. Sometime between 11:00 p.m. and midnight, a witness living in these apartments across the street claimed to hear a scream and multiple footsteps running away from the house in opposite directions.

The next day Knox says she returned home to shower and change clothes. Then she noticed something was wrong. One roommate's room was turned upside down, a rock on the floor and a broken window. Meredith Kercher's door was locked, and she wasn't answering her cell phone.

E. KNOX: I got the phone calls about when she came to her house and Amanda kept saying I have gotten a hold of everybody. I can't get a hold of Meredith. She's not answering her phone. Her door is locked. There was lots of concern. And I said, OK. You know, call the police, and she did, and, you know, the police came, and then they had actually one of the other roommates' boyfriends broke down the door because the police wouldn't do it.

GRIFFIN: Behind Meredith's bedroom door was her body covered by a blanket, blood everywhere. Meredith had been sexually assaulted, stabbed, and slashed in the neck. A bloody handprint left on the wall. Bloody footprints on the floor.

As police began to process the crime scene, suspicion soon began to fall upon Amanda. Partly due to what police believed was a faked forced entry through the window. Observers also thought Amanda's behavior was odd. She and Raffaele stayed in the living room while the others broke into Meredith's room. Francesco Maresca is an attorney hired by the victim's family. He says Amanda's behavior was enough to make her a suspect.

FRANCESCO MARESCA, MEREDITH KERCHER'S ATTORNEY (through translator): The famous behavior of Amanda Knox cannot be justifiable if we compare it to the way normal people behave.

GRIFFIN: In this video, Amanda and her boyfriend, Raffaele, comfort each other outside the house. But at the police station witnesses say they laughed and made faces, heightening suspicions about them.

To Amanda Knox and Raffaele Sollecito, the police station would become all too familiar over the coming days. Her father, Curt, recalls the week affect the grisly discovery.

CURT KNOX, AMANDA KNOX'S FATHER: Between the time that they actually found Meredith and when Amanda was arrested, there was roughly a 90- hour time frame and I'm ball parking the numbers there. During that time, Amanda was in the police station for questioning for I believe it was, 52 hours.

GRIFFIN: As the days passed, the interrogations became longer and more intense. Without a lawyer, Amanda continued to talk to the police, a decision her mother, Edda Mellas, regrets to this day.

MELLAS: You know, would have, could have, and should have. I should have insisted that she leave the country. I should have insisted that she not talk to anybody. I should have gotten her a lawyer immediately.

GRIFFIN: Meanwhile, media interests surrounding the crime began to surge. Information was leaked to the press almost daily. Reports stating the victim knew her killer, or even a woman committed the crime went viral. Soon articles were reporting that Meredith Kercher was the victim of a sex game gone wrong.

C. KNOX: In Italy, you could make up a story or you could say you heard it from some guy that was lying in a ditch, and you can write the story, and then all of a sudden it goes viral.

GRIFFIN: As the media circus grew, so did the pressure on police to solve the case. On the night of November 5, the police interrogated Amanda all night and into the next morning. It was during this session Amanda confessed she was at the house that night. Her boss, Patrick Lumumba, was there as well.

At that point Amanda Knox officially ceased to be a witness. She became the suspect.

The police held a press conference later that day announcing to the world they had solved the crime, case closed. According to police, Meredith Kercher had been killed because she would not take part in a sex game, a sex game orchestrated by Amanda Knox, her boyfriend, Raffaele and Patrick Lumumba.

MARESCA (through translator): I have always said that this is a crime that was born of succession. It was step by step. There was no planning.

GRIFFIN: All three were arrested and charged with murder, but the tabloid press turned their attention to one of the accused in particular, Amanda. When the papers hit newsstands next day, Foxy Knoxy would be all over the front page. In the weeks and months that followed their arrests, new evidence would emerge. A knife found in Raffaele's apartment, both Amanda's and Meredith's DNA on it. Meredith's bra clasp tested positive for Raffaele's DNA.

A homeless man came forward claiming to have seen the couple near the house on the night of the murder.

MELLAS: We kept thinking, oh, this is a big mistake. It will get cleared up, and then it just got really weird with the trial, and, you know, it just kept going and going and going.

GRIFFIN: The world was captivated. Two attractive young women, one accused of killing the other.

(on camera): So what really did happen to Meredith Kercher and is Amanda Knox guilty of murder? For the next hour, forget everything you know.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

(BEGIN VIDEOTAPE)

GRIFFIN (voice-over): With an investigation nearly finished and three people under arrest, the press began to focus on who is Amanda Knox? The picture they painted wasn't very flattering.

D. KNOX: I think some of the biggest problems that have happened with my sister have come from the media. The whole angel-faced with cold eyes, the whole "Foxy Knoxy" thing.

GRIFFIN: To know the real Foxy Knoxy, you have to go back to Amanda's hometown, Seattle, Washington.

MELLAS: Amanda was born here in Seattle in the summer of 1987, the day before I turned 25, so our birthdays are one day apart.

GRIFFIN: Born into a middle-class family, her mother a schoolteacher, her father an accountant, divorced when Amanda and her sister were still very young.

D. KNOX: And so growing up, it was -- I spent the majority of my time with my mom. It was every other weekend that me and Amanda went to our dad's.

GRIFFIN: Always active, Amanda earned her nickname Foxy Knoxy at a young age and not from where you might have thought.

(on camera): And soccer is where she earned that nickname that...

MELLAS: Oh, yes.

GRIFFIN: ... that's come back to haunt her, Foxy Knoxy. MELLAS: Oh, yes, at the age of eight. You know, the 8-year-olds who don't know anything but call each other all kinds of funny nicknames gave her Foxy Knoxy.

GRIFFIN (voice-over): She was not a typical teenager. Amanda was driven and focused, unlike most eighth graders, Amanda wanted an academic challenge. So for high school, she chose Seattle prep, a prestigious private school that her parents could not afford.

C. KNOX: Amanda was scholarship out to Seattle prep, so it's not like she was given a silver spoon or anything by any means.

GRIFFIN: Chris Johnson, an English teacher at Seattle prep recalls a girl who was different from her classmates.

KRIS JOHNSON, AMANDA KNOX'S ENGLISH TEACHER: She was so diligent that she signed up for an extra English class at a time when she could have had a free period. She took an extra class so she stood out.

GRIFFIN: And as for boys...

(on camera): Did she have many serious boyfriends before?

D. KNOX: No. She was definitely a very late bloomer. I don't even remember a boyfriend until college.

GRIFFIN (voice-over): She knew very early on that she wanted to see the world.

MELLAS: I think Amanda started talking even in middle school about wanting to travel and to see different places.

GRIFFIN: Amanda would take her love of adventure to the University of Washington where she would major in linguistics. Her friend Andrew Seliber describes a woman open to the world.

ANDREW SELIBER, AMANDA KNOX'S FRIEND: I think it was her just open personality to you know, see the good things in people and have always a positive attitude about everybody and everything in the world.

GRIFFIN: In college, Amanda knew she wanted to spend a year abroad, but to do that; she would have to raise money that her parents did not have.

(on camera): How did she do it?

MELLAS: She had to save $10,000. She lived extremely frugally and spent no money on anything and then worked several jobs at a time, numerous jobs at a time, saved every penny.

GRIFFIN (voice-over): Amanda chose to study in Perugia, Italy, a small town in the center of the country. In the late summer of 2007, Amanda and her sister, Deanna, traveled there to get her settled. On the very first day in town, Deanna found Amanda place to live. D. KNOX: We were walking around, and the first thing Amanda did, of course, was go down to her university. So we walked down there, and she went inside, and I sat outside and this girl came up and was posting something on the fence right next to where I was sitting. And I looked over, and it said all I could read because I don't speak Italian was "apartmento."

GRIFFIN (on camera): And that was the apartment?

D. KNOX: Uh-huh. That was it.

GRIFFIN (voice-over): Once settled in Perugia, Amanda seemed to be living her dream.

C. KNOX: The first set of pictures she ever sent me were of the little house that she had found you know, and I was kind of looking at her going you have that kind of a view out of your backyard? And it was really you know I was very happy for her.

GRIFFIN: And just eight days before Meredith's murder, Amanda met a boy, an Italian student named Raffaele Sollecito.

(on camera): Was she falling in love? Did she sound like a girl falling in love?

MELLAS: I thought you know, she sounded like a girl who was definitely very infatuated with this young man who was showing her around, you know, they went over to Assisi. So, yes, there was definitely a big infatuation there. I don't think they had time to fall in love by the time they were arrested.

GRIFFIN (voice-over): Amanda Knox, devoted daughter, student, lover? According to this man, murderer.

(on camera): Is Amanda Knox evil?

(END VIDEOTAPE)

(COMMERCIAL BREAK)

(BEGIN VIDEOTAPE)

GRIFFIN (voice-over): Almost immediately after police say she confessed to her crime, Amanda Knox recants. She tells her parents she broke under stress. In court, she would tell jurors how a police officer struck her from behind, how she was denied water, food, a translator and how she says under pressure by police she was asked repeatedly to dream up, imagine scenarios for how it could have happened.

CNN traveled to Perugia, Italy, to sit down with the prosecutor of Amanda Knox. For three hours, Giuliano Mignini answered our questions and his critics that he prosecuted Knox with little evidence, that he played on erosion motions and rumor rather than facts and the linchpin of his case, the so-called confession of Amanda Knox, was coerced out of a frightened college student. GRIFFIN (on camera): Nobody hit her?

GIULIANO MIGNINI, PROSECUTOR (through translator): No, absolutely not.

GRIFFIN: Was she asked to imagine scenarios? So she's lying?

MIGNINI (through translator): Absolutely. You either see the person or not. I can't ask a person what he or she imagines. This question would make no sense.

GRIFFIN (voice-over): That's not all that wouldn't make sense because it turns out virtually everything Amanda Knox told her interrogators the night of her so-called confession was a lie.

Amanda Knox in this statement told police she was in the house the night of the murder and saw her boss, nightclub owner Patrick Lumumba, and Meredith Kercher go into Meredith's room, and she heard screams.

Amanda's statement adds: "I am very confused. I imagined what could have happened." Police apparently didn't bother to check the facts about Lumumba. They immediately arrested Amanda Knox, Raffaele Sollecito and Patrick Lumumba for the murder of Meredith Kercher, Mignini and police announcing to the public, case solved.

Giuliano Mignini admitted to us, even without any evidence, he knew almost the moment he arrived and laid eyes on Amanda Knox and Raffaele Sollecito, they were involved in the murder.

(on camera): Prior to the forensic investigation, prior to everything really, your intuition or your detective knowledge led you to Amanda Knox and Raffaele Sollecito?

MIGNINI (through translator): After the first few weeks we were convinced because of the behavior of the two people and especially Amanda that they were both involved in a crime.

GRIFFIN (voice-over): But almost immediately after the arrests, Mignini had a problem. The third suspect, Patrick Lumumba, had an airtight alibi. He was in his crowded bar that night. He could not have been involved. Then the actual forensic tests came back.

GREG HAMPIKIAN, FORENSIC SCIENTIST: When I looked at it, I was horrified.

GRIFFIN: Greg Hampikian is a forensic scientist and director of Idaho's Innocence Project. He also was working with the Knox defense team.

He says Italian investigators did a good job processing the crime scene, collected excellent evidence, but clung to shakier evidence that proved their theory, a classic error, says Hampikian, a prosecutor who trusted his gut feeling, instead of the science that at that time was pointing to another suspect. HAMPIKIAN: They didn't like the way Amanda behaved, whatever that means, and so they wanted to investigate her and Raffaele and her boss. When the DNA is finally processed, it's not any of their suspects. So what do you do? What would you do? You let them go.

GRIFFIN: As Patrick Lumumba was being released from jail, investigators analyzing the bloody evidence left at the crime scene found an entirely new suspect. His name? Rudy Guede, a known petty criminal from the Ivory Coast who fled to Germany shortly after the murder. It turns out Guede's handprint made in Meredith Kercher's own blood was found in the victim's room.

Guede's DNA found inside the victim's body in her vagina. His DNA on her clothing, on his purse, his feces even found on used toilet paper left near an unflushed toilet down the hall and something else. Guede didn't even know Raffaele and had only met Amanda a few times with neighbors.

C. KNOX: Knowing all of that and when he got extradited from Germany back to Italy, we thought, thank God, this is over.

GRIFFIN: It wasn't.

Prosecutor Mignini simply swapped suspects. Amanda Knox, Raffaele Sollecito and now Rudy Guede had come to Meredith Kercher hoping to include her in an orgy. When Kercher refused, they pulled out knives and killed her. Giuliano Mignini would stick to his instincts despite forensic evidence.

(on camera): You were fixated, according to the defense, on Amanda Knox and Raffaele Sollecito and kept imaging new scenarios that made these two people guilty.

MIGNINI (through translator): No, absolutely not. I did what I did because I was convinced given the evidence that had been gathered that they were responsible. I am absolutely convinced.

GRIFFIN: Rudy Guede, the African drifter, was quickly convicted and sent to prison, implicating Amanda and Raffaele, after which his sentence was reduced.

In 2009 Mignini would bring his case against Amanda Knox and her boyfriend to trial.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

GRIFFIN (voice-over): One of Italy's most notorious murder trials, the case against Amanda Knox and her boyfriend, was getting under way. Basing his case mainly on circumstantial evidence, the prosecutor, Giuliano Mignini, would begin to present witnesses. One who claims to have seen the couple near the home the night of the murder. Two others would come forward, saying they heard a scream. One of them also hearing footsteps running in different directions. But Mignini now would also present scientific evidence, he said, that proves Amanda and Raffaele's guilt. Two DNA samples: Raffaele's skin cells on Meredith's bra clasp, collected 46 days after police first showed up at the murder. And what one expert called an inconclusive sample of what could have been Meredith's DNA found on a knife collected at Raffaele's apartment. On the handle of the knife, Amanda's DNA.

According to prosecutor Mignini, because the victim had never been to Raffaele's apartment, the knife must be the murder weapon.

But tests for blood on the knife turned up negative. Prosecutors explained it's because the knife had been wiped clean.

Forensic expert Greg Hampikian says finding DNA but no blood makes it highly unlikely the knife was used in a bloody murder. He also says it's surprising the prosecutor was even allowed to admit such a small, unexplainable sample as evidence.

GREG HAMPIKIAN, FORENSIC EXPERT: Would this have made it into a U.S. court? I don't think this would have made it onto a U.S. lab report.

GRIFFIN: What also made it into court was Amanda's so-called confession. In a quirk of Italian law, the confession was thrown out of the criminal case against Knox, but jurors heard it anyway as part of a civil case being tried simultaneously.

In court, jurors heard Mignini's evidence of guilt. Then, when they went home each night, they heard the news from a tabloid press gone wild. Sensational headlines about the murder suspect, dubbed Foxy Knoxy, were rampant. Completely fabricated stories of how Amanda Knox engaged in sexual orgies, satanic rituals, how she bought bleach to clean up the crime scene. All of it, according to the prosecutor himself, lies.

With no conclusive evidence their daughter was guilty, the Knox family would enter the courtroom just after midnight on Saturday, December 5, 2009, believing prosecutors had simply not proved the case. The jury had deliberated for 13 hours. In a moment that haunts him to this day, Curt Knox heard the verdict in Italian. Guilty.

CURT KNOX, AMANDA'S FATHER: These two kids were innocent, and to have them, you know, say, "Guilty," it was just devastating. It was literally devastating. And, you know, I mean literally, the people that were in the courtroom were kind of like, "Ohh!"

GRIFFIN: Doug Preston is a best-selling author who dreams up chilling murder plots in his writing shack on the cold coast of Maine. Thirteen years ago, he had an idea to write a chilling tale, but in a warmer location.

DOUG PRESTON, AUTHOR: I moved to Italy to write a novel, and we rented a house in the Tuscan hills just outside of Florence.

GRIFFIN: His research began with trying to learn about the Italian justice system. Teaming up with an old Italian crime reporter named Mario Spezi, he soon was intrigued about a serial killer Italy had yet to catch, the Monster of Florence," who killed eight couples from 1968 to 1985, then vanished.

PRESTON: When you're a novelist, you're just making things up. But this was real.

GRIFFIN: Preston would quickly abandon his work of fiction for the real thing and began to learn how the Monster targeted young lovers engaging in sex, mostly in cars in the hills above Florence, killing first the man, then dragging the woman out of the car, mutilating and removing her genitals.

For 17 years always using the same gun, the same knife, killing again and again as police failed to solve the case.

PRESTON: Yes, again and again the police arrested innocent people, interrogated them brutally, thought that they had extracted all kinds of really important confessions from them.

GRIFFIN: Preston says with the suspects in custody, the Monster would kill again. Police chased wild theories of a satanic cult. Preston and Spezi began to write of a lone killer and terrible police work.

PRESTON: The book, you know, to be honest, really criticized their investigation very thoroughly, and it wasn't just criticism. It presented irrefutable evidence that the police were on the wrong track.

GRIFFIN: Before the book could even be released, police focused their attention on the authors. Mario Spezi's villa was raided, his notes confiscated and the journalist placed under arrest, though later released without charges. Police surmised Spezi knew so much about the killer that he just might be the killer.

Then Preston's phone rang.

PRESTON: I thought it was a joke. And then they said, "No, Mr. Preston, this is not a joke. We are coming to get you. This is obligatory. You tell us where you are. That will save everyone a lot of trouble."

GRIFFIN: Preston would find himself at the door of the prosecutor's office here in Perugia, where he thought he'd spend a few minutes answering just a few questions.

PRESTON: I had never understood how brutal, psychologically brutal an interrogation is. You feel absolutely helpless.

GRIFFIN (on camera): And the chief interrogator was and is?

PRESTON: Giuliano Mignini, this prosecutor who -- let me tell you something, he knows exactly what he's doing.

GRIFFIN (voice-over): Mignini was the prosecutor for both the Monster and the Amanda Knox cases. Just like during Amanda's interrogation, Preston also says he was asked to imagine scenarios of how the crime could have occurred.

PRESTON: I was terrified. I thought, these people have the power to put me in jail for the rest of my life.

GRIFFIN: Preston says he was questioned for two hours. He left the meeting and wrote everything down, including the time he went in and the time he left, which is why Giuliano Mignini's recollection of that meeting with Preston is so puzzling.

GIULIANO MIGNINI, PROSECUTOR (through translator): It lasted about 20 minutes. No more than that. And it was the first time I had met Preston. Around 20 minutes.

GRIFFIN (on camera): I interviewed Doug Preston, and that is just not true, according to him. He said the interrogation lasted two hours.

MIGNINI (through translator): I don't remember now how long he was interviewed for. I believe it was about 20 minutes. Perhaps half an hour. Perhaps -- who knows? -- about an hour. I'd have to look at the statement.

However, what is certain is that when you make a statement, that person must tell the truth, and I challenge some of the things he said.

GRIFFIN: And let me read to you what he said about it: "I began to sweat. The public minister began repeating the same questions over and over again."

PRESTON: And so I said, wait a minute. I said, "Are you -- are you -- do you think I've committed a crime?"

And that's when Mignini said, "Yes, we don't think it. We know it. We know you have committed a crime. We have the proof. And you are going to confess to it."

GRIFFIN: It sounds very similar to what Amanda Knox described.

MIGNINI (through translator): It is completely different because I interrogated Preston. Amanda was interrogated by the police. Preston wasn't arrested. Amanda was arrested. The two things are completely different. They have absolutely nothing in common apart from the fact that I was the public prosecutor in both cases.

GRIFFIN (voice-over): Amanda Knox describes to her lawyers the very same techniques: aggressive questioning, asking to speculate, confronted with so-called evidence of criminal activity that police didn't have.

Fearing he would soon be arrested, in 2006 Preston fled Italy and has never returned.

But the tables were beginning to turn for the prosecutor, as the main witness against Amanda Knox was called into question.

(COMMERCIAL BREAK)

GRIFFIN (voice-over): For decades now, Italian prosecutors have tried and have failed to catch the Monster of Florence, who shot and mutilated eight couples in the Tuscan hills.

Prosecutor Giuliano Mignini's investigation would also end in failure. His case against journalist Mario Spezi was completely thrown out, and his theory of a satanic cult and massive cover-up in the Monster case was being ridiculed by other Italian justices.

And in his investigation into Kercher's death, he would not wait for the forensic evidence to be processed. He already had his suspicions. Within days he announced the horrific crime was solved.

(on camera): Dr. Mignini, is it possible that a prosecutor who was facing his own troubles perhaps rushed to judgment to solve a sensational crime?

MIGNINI (through translator): I did not take any opportunity, because that day, I just happened to be on duty. A tour of duty of a week. So I did not take an opportunity.

GRIFFIN (voice-over): The morning after our interview with Giuliano Mignini, the prosecutor spotted our camera, walked towards me, and off camera asked what I thought of the interview the night before. If I thought he was being truthful.

Clearly, Mignini was concerned about his own reputation and his case against Amanda Knox.

The tabloid press, still enamored by Foxy Knoxy, was beginning to tell a different story. Amanda and Raffaele had appealed their convictions, and a new judge and jury were in the driver's seat. The appeal hearing was under way.

By now, they had both been imprisoned for four years. Raffaele Sollecito shaved his head. Knox rarely smiled. Knox's family said the couple, who had met just eight days before the murder, hadn't communicated since their arrest.

March 26, 2011, Amanda mouths to Raffaele, "Are you OK?" It is a tender moment in what would be a strange hearing.

Amanda Knox's attorney cross-examine an old witness. He is the homeless man who lived in this park and originally told the court he saw Amanda and Raffaele near the crime scene the night of the murder. Before any testimony, cameras are ushered out of the court, and the police bring in the star prosecution witness that the jury would find laughable.

The homeless heroin addict could no longer remember the exact night he saw the couple. He was confused. It could have been Halloween; actually, the night before the murder. And then the star witness dropped the bombshell, admitting he was under investigation by Mignini's office for heroin dealing at the exact moment he became one of Mignini's star witnesses.

In our interview the night before, Giuliano Mignini told us he has no doubts the tramp, as he calls him, was telling the truth.

MIGNINI (through translator): If he says he saw them and states it under oath, then we have to believe him, unless given reason not to. It's not as if the crime had been filmed. I wish it had been.

GRIFFIN (on camera): Was he offering his testimony in hopes of getting a favor in court?

MIGNINI (through translator): No, he didn't get any favor at all. The witness presented himself and gave a statement. That's all. We took his statement because the evidence was relevant.

GRIFFIN: So you believe the testimony of a homeless heroin dealer?

MIGNINI (through translator): I don't want to comment on the judicial proceedings regarding this individual, because he was tried for another matter, something completely different that had nothing to do with this trial. And so for this trial, he is a witness.

GRIFFIN (voice-over): With Mignini's main witness heavily scrutinized, it left only the scant DNA evidence. And that, too, was about to be challenged.

(COMMERCIAL BREAK)

GRIFFIN (voice-over): With the prosecution's main witnesses being challenged on appeal, the case against Amanda Knox and Raffaele Sollecito seems to be hanging on two very small pieces of DNA evidence.

Two months after our interview with prosecutor Giuliano Mignini, a court-appointed review of the forensic evidence would find the evidence itself worthless. The spot found on the knife, it turns out, was not even blood, and the DNA evidence on the bra clasp is so small, it is scientifically worthless. Further testing impossible because the genetic material, if there was any, was ruined in police storage.

Mignini still insists the forensic evidence proves his case, but the independent Italian experts have determined the evidence should not be used. It is a final blow to Mignini's prosecution.

(on camera): Do you have any doubt, any doubt in your mind, that you convicted the wrong people?

MIGNINI (through translator): Listen, I am very sincere, so if I made certain requests, it was because I was absolutely sure that they were responsible. Otherwise, if I had had any doubt, I would have asked for an acquittal for lack of evidence.

GRIFFIN (voice-over): October 3, 2011. The appeals case is now complete. Amanda Knox is allowed to address the judge and jury for a final time. After four years in an Italian prison, she speaks fluent Italian and begs them to let her go.

AMANDA KNOX, MURDER DEFENDANT (through translator): I haven't done the things they're suggesting I have done. I haven't murdered; I haven't raped; I haven't stolen. I wasn't there. I wasn't present at the crime.

GRIFFIN: Hours later, a verdict is reached. Amanda Knox and Raffaele Sollecito are escorted into court for the final time. And as the verdict is read, Knox realizes the jury believes her story and sinks into the arms of her attorney. The murder convictions are overturned. Both Sollecito and Knox are to be set free immediately.

Thirty hours after a sobbing Amanda Knox leaves an Italian court, a now smiling Amanda Knox and her family arrive to cheers in Seattle. Amanda Knox is home, speechless, but finally approaches the podium. It's the first time she has spoken publicly since her release, and as she approaches, she's reminded this time to speak in English.

KNOX: Thank you to everyone who's believed in me, who has defended me, who has supported my family. I just want -- my family's the most important thing to me right now, and I just want to go and be with them, so thank you for being there for me.

GRIFFIN: For the past year and a half, Amanda has spent time with her family and friends, studied creative writing at the University of Washington, got reacquainted with her old boyfriend, Raffaele Sollecito.

RAFFAELE SOLLECITO, ACQUITTED OF MURDER: We talk about family, about relationship with friends, about movies, books. We are almost a brother and sister.

KNOX: She also has a new boyfriend, James Torano. The two reportedly live together in Seattle. Things were finally becoming normal again. But her ordeal was not over.

UNIDENTIFIED FEMALE: Also shock waves in Italy.

GRIFFIN: After the prosecutor appealed his case, Italy's highest court announced a shocking decision Tuesday: to overturn her acquittal.

Amanda Knox's attorney, Ted Simon, said the ruling was disappointing, but it's hardly a time to panic.

TED SIMON, ATTORNEY FOR AMANDA KNOX: The supreme court has a much narrower scope of review. All they're supposed to do is to look and see whether or not the appellate court jury acted within its jurisdiction and according to the proper rules. It does not re- litigate or it does not reconsider or re-evaluate or reopen the facts. And that's why everyone remains reasonably hopeful without prejudging what they will do.

GRIFFIN: For Amanda Knox, it's now a waiting game.

SIMON: She, as well as her family, have acted with the, you know, utmost courage, persistence, patience, grace, dignity throughout all these proceedings. But like everyone else, they're waiting for what the decision will be.

GRIFFIN: And if she's ultimately convicted again?

JEFF TOOBIN, CNN LEGAL ANALYST: The Italian government may say to the United States, "Bring us Amanda Knox. She's been duly convicted in our courts. You have signed an extradition treaty with us. We want her back."

SIMON: So all this discussion really about extradition is not nearly in play. And the other thing you should know, that you know, while we are hopeful that they will simply affirm this prior wrongful conviction, you know, there is nothing that would lead anyone to believe in any of the evidence that there would be any other verdict but one of "not guilty," because there simply is an absence of evidence in this case.

GRIFFIN: Unlike in years past, time is now on Amanda's side.

TOOBIN: The Italian legal system, the extradition system, time doesn't get measured in months. It gets measured in years. She is looking at many years of legal proceedings, but also many years of freedom in the United States before there's even the possibility that she's extradited back to Italy.

GRIFFIN: No small comfort to a 25-year-old woman who just wants to put the nightmare behind her.