Amanda Knox has told an Italian appeal court her conviction for the murder of British student Meredith Kercher was an "enormous mistake".
The 23-year-old American is trying to overturn her conviction after being jailed last year for 26 years for the killing in Perugia in 2007.
In an emotional address to a court in Perugia, Knox said her life had been "broken" by three years in jail.
Miss Kercher, 21, from Coulsdon, south London, was found with her throat cut.
The Leeds University student's semi-naked body was found partially covered by a duvet in her bedroom in the house she shared in the Italian city.
Knox's former boyfriend, Raffaele Sollecito, was jailed for 25 years for the murder.
During her address to the appeal court, Knox said she is not the "dangerous, diabolical" person described by the prosecution.
She became tearful as she told how she thought of Miss Kercher as someone she was "grateful and honoured" to have met.
Reading in Italian from handwritten notes, she said: "I am unjustly convicted.
"I will never get used to this broken life. To Meredith's family and loved ones, I would like to say that I am sorry that Meredith is not here.
"What you're going through and what Meredith went through is incomprehensible and unacceptable."
She added: "I am innocent. Raffaele is innocent. We did not kill Meredith.
"It doesn't do justice to Meredith and her loved ones to take our lives from us.
"I stand here more scared than ever, not because I am or I have ever been afraid of the truth but because the truth has not been recognised."
She also apologised to Patrick Lumumba, the man she indicated as the possible culprit during police questioning after the killing.
"I should have withstood the pressures that made me do you wrong," she said.
Knox was charged last month with slander for claiming police beat her during questioning.
The original trial heard the pair had cornered Miss Kercher after starting a sex game with Ivorian drug dealer Rudy Guede, who was jailed for 30 years for the killing, although that was reduced to 16 years on appeal.
Sollecito is appealing together with Knox, and during the appeal session his lawyers questioned the reliability of the evidence against him.
The appeal had previously been adjourned because one of the lawyers is five months pregnant and has been advised not to travel to the court from Rome.
Knox's defence team maintains that the DNA evidence in the case was inconclusive and has argued it may have been contaminated when analysed.
It particularly focuses on disputed traces of DNA found on the knife the prosecution said was used in the murder, and on the clasp of Miss Kercher's bra.
In their appeal motion, defence lawyers were sharply critical of the verdict, maintaining it was based on mere hypotheses and saying that the motive was absent.
Knox's parents, from Seattle, have said they are hopeful their daughter will be released once judges in Italy have re-examined the evidence.
However, if her conviction is upheld, her sentence could be increased.
The next hearings are scheduled for 18 December and 15 January and the outcome of the trial is expected next year.
As in the original trial, the verdict will be decided by the judge, a fellow magistrate and six jurors.