PERUGIA, Italy >> An Italian appeals court threw out Amanda Knox’s murder conviction today and ordered the young American freed, a stunning reversal four years after she was jailed for the sexual assault and stabbing death of her British roommate.

Knox, 24, collapsed in tears after the verdict overturning her 2009 conviction was read out, her lawyers draping their arms around her in support. Her co-defendant, Italian Raffaele Sollecito, also was cleared of killing 21-year-old Meredith Kercher in 2007.

The ruling clears the way for Knox to leave Italy, and about 90 minutes after the verdict was handed down a convoy of cars was seen leaving the prison. Nothing in Italian law would prevent her from returning home to Seattle, even if prosecutors appeal the acquittal to Italy’s highest court, legal experts say.

One of Knox’s lawyers, Carlo della Vedova said he didn’t know when Knox would leave the country. Knox needed to renew her passport, but it’s not clear how quickly that could be done or if the paperwork was already completed.

"We’re thankful that Amanda’s nightmare is over," her little sister Deanna Knox told reporters outside the courthouse. "She suffered for four years for a crime she did not commit."

She then asked for privacy for the family so they could "recover from this horrible" ordeal.

The eight-member jury acquitted both Knox and Sollecito of murder after a court-ordered review of the DNA evidence cast serious doubts over the main DNA evidence linking the two to the crime.

The jury had two options to acquit: determining there wasn’t enough evidence to uphold the conviction or that they simply didn’t commit the crime. The jury determined the latter, clearing them completely.

The jury upheld Knox’s conviction on a charge of slander for accusing bar owner Diya "Patrick" Lumumba of carrying out the killing. But he set the sentence at three years, meaning for time served. Knox has been in prison since Nov. 6, 2007.

The Kercher family looked on grimly and a bit dazed as the verdict was read out by the judge after 11 hours of deliberations. Outside the courthouse, some of the hundreds of observers shouted "Shame, shame!"

"We respect the decision of the judges but we do not understand how the decision of the first trial could be so radically overturned," the Kerchers said in a statement. "We still trust the Italian justice system and hope that the truth will eventually emerge."

The victim’s sister, Stephanie Kercher, who was in Perugia with her mother and brother for the verdict, lamented that her sister "has been nearly forgotten."

"We want to keep her memory alive," she said after the verdict.

Yet inside the frescoed courtroom, Knox’s parents, who have regularly traveled from their home in Seattle to Perugia to visit Knox over the past four years, hugged their lawyers and cried with joy. Knox herself was so overwhelmed with tears that two guards tugged on her arms to escort her out of the courtroom.

The trial has captivated audiences worldwide: Knox and Sollecito, who had just begun dating, had been convicted of murdering Meredith in what the lower court said had begun as a drug-fueled sexual assault.

The U.S. State Department said it appreciated the "careful consideration" the Italian justice system gave to the case. "Our Embassy in Rome will continue to provide appropriate consular assistance to Ms. Knox and her family," spokeswoman Victoria Nuland said after the verdict.

Also convicted in separate proceedings was Rudy Hermann Guede, a small-time drug dealer and drifter who spent most of his life in Italy after arriving here from his native Ivory Coast. Guede was convicted in a separate fast-track procedure and saw his sentence cut to 16 years in his final appeal.

Lawyers for Knox and Sollecito charged that Guede was the sole killer, but the prosecution and a lawyer for the Kercher family said that bruises and a lack of defensive wounds on Kercher’s body prove that there was more than one aggressor holding her into submission.

In Seattle, about a dozen Knox supporters were overjoyed that she has been cleared of the murder conviction.

"She’s free!" and "We did it!" they shouted at a hotel where they watched the court proceedings on TV.

Prosecutors can appeal the acquittal to Italy’s highest court. There was no word late Monday if they planned to do so.

Earlier today, Knox tearfully told the court she did not kill her roommate. Knox frequently paused for breath and fought back tears as she spoke in Italian to the eight members of the jury in a packed courtroom, but managed to maintain her composure during the 10-minute address.

"I’ve lost a friend in the worst, most brutal, most inexplicable way possible," she said of the 2007 murder of Kercher, who shared an apartment with Knox when they were both students in Perugia. "I’m paying with my life for things that I didn’t do."

Knox and Sollecito, Knox’s former boyfriend from Italy, were convicted in 2009 of sexually assaulting and murdering Kercher, who was stabbed to death in her bedroom. Knox was sentenced to 26 years in prison, Sollecito to 25. They both deny wrongdoing.

"I never hurt anyone, never in my life," Sollecito said Monday in his own speech to the jury.

The prosecution’s case was fatally set back during the appeal when two court-ordered independent experts reviewed the DNA evidence that had been used to link the two to the crime during the first trial.

Prosecutors maintain that Knox’s DNA was found on the handle of a kitchen knife believed to be the murder weapon, and that Kercher’s DNA was found on the blade. They said Sollecito’s DNA was on the clasp of Kercher’s bra as part of a mix of evidence that also included the victim’s genetic profile.

But the independent review — ordered at the request of the defense, which had always disputed those findings — reached a different conclusion.

The two experts found that police conducting the investigation had made glaring errors in evidence-collecting and that below-standard testing and possible contamination raised doubts over the attribution of DNA traces, both on the blade and on the bra clasp, which was collected from the crime scene 46 days after the murder.

The review was crucial in the case because no motive has emerged and witness testimony was contradictory. The prosecutors refuted the review and stood by their original conclusions.

Hundreds of eager observers gathered outside the courthouse ahead of the announcement, joining television vans that have been camped out for more than a week. One hundred reporters were allowed into the subterranean courtroom.

Observers lined the street leading to the courthouse, taking pictures as the two vans carrying Knox and Sollecito from the prison to the court passed by.

Kercher’s mother, sister and a brother traveled to Perugia for the verdict. They had expressed worry over the possibility of an acquittal but told reporters as deliberations were under way that they hoped the jury would do the right thing and not be influenced by the media’s focus on the case.

The family, however, said it could understand the Knox family’s media campaign.

"They fully believe in her innocence. You can’t blame them for that," said Lyle Kercher, the victim’s brother. "But it’s obviously hard for us."

As the verdict was broadcast live, hundreds of reporters and camera crews filled the underground, frescoed courtroom before Knox’s address, while police outside cordoned off the entrance to the tribunal.

Knox insisted today that she had nothing to do with the murder and that Kercher was a friend who was always nice to her. Gesticulating, at times clasping her hands together, the American said she has always wanted justice for Kercher.

"She had her bedroom next to mine, she was killed in our own apartment. If I had been there that night, I would be dead," Knox said. "But I was not there."

"I did not kill. I did not rape. I did not steal. I wasn’t there," Knox said.

Sollecito was anxious as he addressed the court, shifting as he spoke and stopping to sip water. He said prior to the Nov. 1, 2007 murder was a happy time for him, he was close to defending his thesis to graduate from university and had just met Knox.

The weekend Kercher was murdered was the first the pair planned to spend together "in tenderness and cuddles," he said.

At the end of his 17-minute address, Sollecito took off a white rubber bracelet emblazoned with "Free Amanda and Raffaele" that he said he has been wearing for four years.

"I have never taken it off. Many emotions are concentrated in this bracelet," he said. "Now I want to pay homage to the court. The moment to take it off has arrived."