Italy's highest court overturned the murder conviction against Amanda Knox and her ex-boyfriend Friday over the 2007 slaying of Knox's roommate, bringing to a definitive end the high-profile case that captivated trial-watchers on both sides of the Atlantic.

"Finished!" Knox's lawyer Carlo Dalla Vedova exulted after the decision was read out late Friday. "It couldn't be better than this."

In a rare decision, the supreme Court of Cassation overturned last year's convictions by a Florence appeals court and declined to order another trial. The judges declared that the two did not commit the crime, a stronger exoneration than merely finding that there wasn't enough evidence to convict.

In a statement issued from her home in Seattle, Knox said she was "relieved and grateful" for the decision.

"The knowledge of my innocence has given me strength in the darkest times of this ordeal," she said, thanking her supporters for believing in her.

Experts have said such a complete exoneration is unusual for the high court, which could have upheld the conviction or ordered a new trial as it did in 2011 when the case first came up to its review on appeal.

The justices' reasoning will be released within 90 days.

The decision ends the long legal battle waged by Knox and Italian co-defendant Raffaele Sollecito to clear their names in the death of British student Meredith Kercher, after they spent nearly four years in prison immediately after the murder.