Italy's highest court acquitted American Amanda Knox of murder Friday, ending her legal saga.

Knox and her Italian ex-boyfriend, Raffaele Sollecito -- who was also acquitted Friday -- had been convicted, acquitted, and convicted in three different trials over the 2007 murder of Knox's flatmate Meredith Kercher in the Italian university town of Perugia.

"I am tremendously relieved and grateful for the decision of the Supreme Court of Italy," Knox said in a statement Friday. "The knowledge of my innocence has given me strength in the darkest times of this ordeal."

The ruling Friday came after a nearly eight-year legal battle on two continents that first sent Knox and Sollecito to an Italian prison for Kercher's murder. The court found the two guilty in December 2009 of murder and sexual assault and sentenced Knox to 26 years in prison, including one year for slander, and Sollecito to 25 years.

"Right now I'm still absorbing what all this means and what comes to mind is my gratitude for life that's been given to me," Knox said late Friday, speaking to reporters outside her mother's Seattle home.

Both were acquitted and freed in 2011 after spending nearly four years in prison.

Knox returned to her hometown of Seattle following the acquittal but was then tried and convicted in absentia and ordered a new appeals trial in 2014.

Lawyers for 27-year-old Knox and Sollecito – who was also appealing the latest conviction for the murder – made a final appeal in court Friday, saying there were errors of "colossal proportions" in the guilty verdict.

Attorney Giulia Bongiorno dissected the 2014 Florence appeals court decision to show what she called errors of fact and logic that resulted in a new prison sentence of 28 1/2 years for Knox while upholding 25 years for Sollecito.

Judges at the high Court of Cassation began deliberating shortly after noon. A decision to confirm the convictions could have resulted in an extradition request for Knox, who is currently free in the U.S.

She has said she would never willingly return to Italy.

In her closing arguments, Bongiorno said even Knox's original statement to police – which was never entered as evidence and was later changed – exonerated her client.

Knox, who along with Kercher had been studying in Perugia, had initially accused a Congolese bar owner of the murder. She also initially told investigators through a translator that she was home the night that Kercher was killed and had to cover her ears to drown out her screams.

Bongiorno said she believed Knox's statement was coerced – but that even if the high court chooses to consider it, Sollecito figures nowhere in her story.

"My heart is crying because I think she was pressured by an intermediary," Bongiorno said, apparently referring to the person who served as Knox's unofficial translator during police questioning. But within that statement, Bongiorno added, Knox "rules out Sollecito."

Kercher, a 21-year-old British exchange student from the University of Leeds, was found murdered Nov. 2, 2007, in the apartment she shared with Knox and two other students. Her throat was slashed and she had been sexually assaulted.

Knox and Sollecito were arrested a few days later along with Rudy Guede, an Ivory Coast native raised in Perugia. Guede was convicted of murder in a separate trial and is serving a 16-year sentence. He acknowledged being in the apartment at the time of the murder and his DNA was found in multiple places in Kercher's bedroom. His conviction specified that he committed the crime with others, and he claimed that Knox and an unidentified man were present.

The Kercher family attorney, Francisco Maresca, was disappointed by the decision.

"I think that's a defeat for the Italian justice system," he said. "Whoever was Guede's accomplice does not have a name."

Knox and Sollecito have always maintained their innocence.

Knox graduated from the University of Washington last year with a degree in creative writing. She recently started working as a freelance reporter for the West Seattle Herald. Knox also wrote a memoir about her life and her experiences in Italy, which was published in 2013. She was paid a reported $4 million.

She plans to marry Colin Sutherland, a musician who recently moved to Seattle from New York.

The Associated Press contributed to this report.