The murder of British student Meredith Kercher by her housemate Amanda Knox was unplanned and was not motivated by hatred or resentment, the judges disclosed today.
American Knox, 22, was jailed for 26 years in December for sexually assaulting and murdering the Leeds University student in Perugia, Italy.
Prosecutors said the brutal killing was carried out after what started as an extreme sex game.
Knox's Italian former lover, Raffaele Sollecito, 25, was also convicted and jailed for 25 years for murder and sexual assault.
The semi-naked body of Miss Kercher, 21, from Coulsdon, Surrey, was found with her throat slit in her bedroom in Perugia in November 2007.
She had been sharing a cottage on her year abroad in the Umbrian hilltop town with Knox, from Seattle, who was also a student.
Prosecutors said Sollecito held Miss Kercher down while Knox stabbed her to death with a 6in (15cm) kitchen knife.
Small-time drug dealer Rudy Guede, 22, from the Ivory Coast, was jailed last October for 30 years for the murder and sexual violence.
In a written judgment spanning more than 400 pages, the judges in the case said it was a chance meeting between the three that led to the murder.