The thought of Amanda Knox killing someone in a moment of anger is "absurd and unrealistic", her former lover Raffaele Sollecito has said.
The pair were convicted last week of sexually assaulting and murdering British student Meredith Kercher, who was stabbed to death in Perugia, Italy, in November 2007.
American Knox, 22, was jailed for 26 years and Italian Sollecito, 25, was jailed for 25 years.
Speaking through his lawyer, Luca Maori, to Italian newspaper Il Messaggero, Sollecito said: "(Amanda) is a very sweet girl."
Knox's promise of "hot sex" as they shopped for underwear after the murder had been misinterpreted, he said.
"We went to buy underwear because all Amanda's stuff had been seized," he told the newspaper.
"Everything that's been said is wrong. It was only a joke.
"Yes, it was about the underwear and Amanda, but it was only a joke."
The incident has been cited as an example of Knox's unemotional response to the discovery of her house mate's body.
Sollecito said he was not in love with Knox now but considered her his "companion in misfortune".
The semi-naked body of Miss Kercher, 21, from Coulsdon, Surrey, was found with her throat slit in the house she was living in in the Umbrian hilltop town of Perugia, where she was studying on her year abroad.
Prosecutors said Sollecito held the Leeds University student down while Knox stabbed her to death with a six-inch kitchen knife after what started as some kind of extreme sex game.
The two committed the killing along with small-time drug dealer Rudy Guede, 22, who was jailed for 30 years last October for murder and sexual violence in relation to the case.
Knox, from Seattle, become a source of media fascination during the trial in Perugia, being alternatively depicted as a wide-eyed innocent and a cold-blooded she-devil.
She had been sharing a house with Miss Kercher and two other women in the Umbrian hilltop town.
During a trial that lasted almost a year prosecutors described how Miss Kercher, a hard working and pleasant young woman, was killed after Knox's hatred, probably fuelled by drink and drugs, boiled over into murderous rage.
But no clear motive seemed to emerge during the trial, with prosecutor Manuela Comodi telling the court last week that "we live in an age of violence with no motive".
Knox and Sollecito are both planning to appeal against the verdicts.Reuse content