Amanda Knox made an impassioned plea to the jury
The verdict in the trial of two students accused of killing Briton Meredith Kercher in Italy is expected to be delivered after 2300 GMT.
American Amanda Knox, 22, and her Italian ex-lover Raffaele Sollecito, 25, deny murder and sexual violence.
Miss Kercher, 21, a Leeds University exchange student from Coulsdon, south London, was found with her throat slit in her Perugia room in November 2007.
Rudy Guede, 22, from Ivory Coast, is already serving 30 years for the crime.
He has launched an appeal after he was convicted in a separate trial.
The family of Meredith Kercher braved large numbers of journalists
Prosecutors in Miss Knox's and Mr Sollecito's trial say Guede was only one of three killers who acted together, under "the fumes of drugs and possibly alcohol".
They claim Miss Kercher was stabbed to death after what had started as an extreme sex game.
Miss Kercher's family arrived at court on Friday, as the jury continued to deliberate, amid a flurry of activity from awaiting journalists and photographers.
Earlier, Miss Knox's sister, Deanna, said as she arrived at court that she was nervous about the outcome and had had a sleepless night.
"The wait is going to be awful. All I want to do is take her home so I've got a good feeling about it. I'm still nervous."
Miss Knox's father, Curt Knox, insisted: "Our attorneys have more than presented evidence that would show that she's innocent."
KEY EVENTS IN CASE
2 November 2007: Miss Kercher found with throat cut
6 November 2007: Police arrest Amanda Knox, Rafael Sollecito and bar owner Patrick Lumumba
19 November 2007: A fourth suspect, Rudy Guede is arrested. Mr Lumumba is released
28 October 2008: Judge Micheli jails Guede for 30 years for killing Miss Kercher
16 January 2009: Trial of Miss Knox and Mr Sollecito begins
18 November 2009: Guede's appeal hearing opens
4 December 2009: Judge and jury retire to consider case
On Thursday, Miss Knox, who has been the subject of intense media interest, told the jury in Italian she should not be branded a killer.
"The first thing to say is that I am not calm," she said.
"I am afraid of being defined as something I am not and by actions that are not mine.
"I'm afraid of having the mask of a murderer forced on to my skin."
She added she was "confused, sad, frustrated" about the two years she had already been in jail awaiting trial.
Miss Kercher had been sharing a house with Miss Knox, from Seattle, while spending a year abroad in Perugia, an Umbrian hilltop town.
Prosecutors claim Mr Sollecito held Miss Kercher down while his then-girlfriend stabbed her to death.
Mr Sollecito told the court on Thursday that no motive had emerged for his alleged role in the murder.
"I am not violent, I never have been. I wasn't at the house [where Miss Kercher died] that night," he said.
However, prosecutor Manuela Comodi argued that "we live in an age of violence with no motive" and suggested the reason for the murder was a mystery.
"We don't know what sparks these things," she said, citing DNA evidence allegedly linking Mr Sollecito to the crime.
ITALIAN LEGAL PROCESS
Decision made by eight-strong jury, composed of six lay people and two judges
Discussions with trial judge before verdict announced
No explanation for verdict will be provided immediately, instead within 90 days
Anyone convicted has 90 days to appeal. If not, the sentence becomes definitive
Appeals heard at the regional Assisi Appeals Court, or at Italy's highest court, the Corte Suprema di Cassazione, for final verdict
She wrapped a white bra around a microphone in the courtroom to demonstrate how his DNA could have ended up on Miss Kercher's bra strap and not on the rest of the garment.
During her defence, Miss Knox had testified that she spent the night of the murder with Mr Sollecito at his flat, where they smoked marijuana, had sex and watched a movie.
In his closing arguments in the trial, her lawyer Mr Dalla Vedova told the court: "There are still many doubts".
He said claims Miss Knox's DNA was found on the handle of the knife alleged to have been used to kill Miss Kercher should be discounted.
The defence has argued the shape of the knife did not match Ms Kercher's wounds.
Mr Dalla Vedova also dismissed a prosecution claim that his client resented Miss Kercher for allegedly saying she was promiscuous.