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

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.

While the court won’t release its reasons for clearing the two for weeks, the discrediting of the DNA evidence was believed to have been the fatal blow to the prosecution’s case in the absence of a clear motive.

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

Even if prosecutors appeal the acquittal to Italy’s highest court, nothing in Italian law would prevent her from returning home to Seattle. An Italian lawmaker who has championed her case, Rocco Girlanda, said she was due to fly out Tuesday from Rome.

About 90 minutes after the verdict was handed down a black Mercedes carrying Knox was seen leaving the prison.

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, five days after the murder.

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 Meredith “has been nearly forgotten.”

Inside the frescoed courtroom, Knox’s parents, who have regularly traveled from their home in Seattle to Perugia to visit her 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.

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.

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

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 bruises and a lack of defensive wounds on Kercher’s body prove there was more than one aggressor holding her down.

After the verdict, 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.

In Seattle, about a dozen Knox supporters were overjoyed.

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

Earlier Monday, Knox tearfully told the court in fluent Italian that she did not kill the woman who shared an apartment with her when they were both students in Perugia. Knox frequently paused for breath as she spoke 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. “I’m paying with my life for things that I didn’t do.”

Knox and Sollecito were convicted 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.

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

The prosecution’s case was 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.

From the start, the weak point in the prosecution’s case was the lack of motive along with unreliable and at times contradictory eyewitness testimony. Therefore, much depended on the scientific evidence gathered by investigators.

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.

Prosecutors spent several hearings and a significant portion of their closing arguments trying to refute the review, attacking the experts as unqualified, standing by their original conclusions and defending the work of forensic police.

They also pointed to what a prosecutor, Manuela Comodi, called “gigantic, rock-solid circumstantial evidence” that contributed to the original convictions.

What led the appeals court to reach its decision will be explained when the court issues the mandatory written motivation -- due within 90 days of the verdict.

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 prison to court passed by.

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

Knox told the court in her final appeal that 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,” she said.

Sollecito was anxious as he addressed the court, shifting as he spoke and stopping to sip water. He said the time before the murder had been a happy one for him. He was close to presenting his thesis to graduate from university and had just met Knox. They had planned to spend that weekend 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.”