Amanda Knox's Italian ex-boyfriend has insisted that he did not kill Meredith Kercher and said the American's evidence provides him with an alibi.
Raffaele Sollecito says the judges who overturned his acquittal based their decision on a Knox statement that proves he was not at the murder scene.
Both he and Knox are currently free while they prepare to appeal against their murder convictions.
Miss Kercher was killed in the flat she shared with Knox in Perugia in 2007.
The prosecution argued that the student from Coulsdon, south London, was stabbed to death after an argument with Knox, and that Knox, Sollecito and another man, Rudy Guede, attacked and murdered her.
Guede was convicted in a separate trial and is serving a prison sentence.
Knox, who is now in the US, and Sollecito were originally found guilty of murder and sexual violence in 2009.
But that ruling was reversed on appeal two years later after doubts were raised about the forensic evidence against them.
In January, a court reinstated the guilty verdicts and Knox was given a 28-year jail sentence, while Sollecito got 25 years.
At a press conference in Rome on Tuesday, Sollecito insisted that he was innocent but said he remained convinced that Knox was too.
Unveiling his new defence strategy, he said January's guilty verdict had been based on evidence from Knox that exonerated him.
"The 25-year prison sentence given to me is based entirely on the statement written by Amanda Knox in pre-trial detention. She herself exonerates me entirely," he told press.
In the statement, she says she was in her flat while the murder was being committed, "with my hands over my ears because in my head I could hear Meredith screaming".
Sollecito is not mentioned by Knox in the text, which his defence team says is proof he was not present at the scene.
"Taking it as read that the judges are right [in basing their verdict on Knox's statement] will you please explain what I have to do with it?" Sollecito said.
Knox later withdrew the statement after saying she had written it under police pressure, and the pair have been each other's alibis since, saying they spent the night together at his house.
Sollecito's lawyer Giulia Bongiorno said that while he has always said he "spent the night" with Knox, he has never said they spent the evening together.
Ms Bongiorno added that her client's appeal would cite a text message that Knox claims to have sent while with Sollecito at his house.
"This text message, according to the court's own ruling, was not sent from his house. Therefore the pair were not together," she said.
Despite throwing doubt on his ex-girlfriend's alibi, the Italian said he had "always believed, and still believe, that Amanda Marie Knox is innocent."
The trial is due next year to go back to Italy's highest court, which could uphold the verdict or order a retrial.
If the verdict is upheld, officials are expected to begin the process of trying to have US citizen Knox extradited to Italy.