After three years in prison, a gaunt-looking Amanda Knox returned to an Italian court Wednesday for a hearing that marked the opening of an appeals trial for the American student convicted of murdering her British roommate.

The hearing lasted only 15 minutes, as the presiding judge agreed to adjourn the case until Dec. 11, when the jury will hear a summary of the first trial and possibly preliminary requests for new evidence and witnesses from the defense.

Knox returned to the same frescoed courtroom where in December she burst into tears as she was convicted of sexually assaulting and murdering Meredith Kercher and given a 26-year prison term.

On Wednesday, the 23-year-old from Seattle, Washington, was escorted by a policewoman — and awaited by a crowd of cameramen and photographers — as she walked across the courtroom and took her usual seat at a desk between her two lawyers. A policeman stood guard behind her.

Wearing a simple light blue hooded sweater, Knox appeared pale and thinner during the brief hearing, in stark contrast to the confident, often smiling image she had projected during most of the first trial. Lawyers said she's been worn out by three years in prison.

"She is tense, exhausted, and has lost weight," Luciano Ghirga, one of her attorneys, said after the hearing.

Her mother Edda Mellas, who was not in court, said on NBC's "Today" that the family, when visiting, has about 10 minutes to talk to her and "she always tries to put on a brave face." But, Mellas said, the family knows the sentence is taking its toll.

"She's just down. She's worried," the woman said. "To be innocent and to be locked up is horrific."

Also attending the hearing in Perugia, a city in central Italy, was her co-defendant and former boyfriend, Raffaele Sollecito. He has been convicted of the same charges and sentenced to 25 years in prison. Both have maintained their innocence.

It was the first time since the two former lovers had seen each other since the December verdict. Lawyers said they exchanged a brief greeting and few words.

They were arrested on Nov. 6, 2007, a few days after Kercher's body was found, stab wounds to her neck and a pool of blood around it, in the apartment she and Knox shared as exchange students in Perugia. Forensic evidence said Kercher was killed the night of Nov. 1.

The defense is seeking a full review of the case, including disputed DNA evidence that was found on a knife allegedly used in the murder and on the clasp of Kercher's bra. The defense maintains that DNA traces were inconclusive, and also contends they may have been contaminated when analyzed. They also note that no clear motive was established.

"There's no motive. There's no physical evidence. There's nothing to connect Amanda to this crime," Edda Mellas said, speaking on ABC'S "Good Morning America."

The prosecutors also have appealed, as they can in Italy, since the ruling fell short of their demand for life in prison.

"We want an acquittal, the prosecution demands a life sentence:

It's an intense, harsh and violent legal clash," Ghirga said in an interview on the eve of the hearing.

Ghirga said that, despite recently being low on confidence, Knox has been eager to get another chance at freedom with the appeal.

"People are starting to learn exactly what this case is really about — which is an issue of wrong conviction," Knox's stepfather, Chris Mellas, told reporters in Perugia. "She is innocent, as is Raffaele, and people are starting to figure that out."

According to the court's reconstruction of the night of the murder, Knox and Sollecito were at the house along with a fourth person, Rudy Hermann Guede, an Ivory Coast citizen who also has been convicted of murder in separate proceedings.

The court found that Knox and Sollecito helped out with Guede's sexual quest for Kercher, before assaulting her brutally together with Guede and ultimately killing her when she resisted. The pair might have found Guede's sexual drive toward Kercher "exciting" or might have been under the influence of drugs, the court said in a document summing up its reasoning in the verdict.

Guede also has denied killing Kercher. His sentence to 30 years in prison was cut to 16 years on appeal.

Knox's defense argued that she spent the night at Sollecito's house, watching a movie, smoking pot and having sex.

The case has drawn large media attention, and the courtroom was packed on Wednesday with journalists, cameramen and photographers. As in the previous trial, Presiding Judge Claudio Pratillo Hellman ruled that cameras would only be allowed to film the defendants' entrances.

The Kercher family did not attend the hearing, but sent a letter to the mayor of Perugia, who has decided to create a scholarship in Kercher's name.

"Meredith loved Perugia and had made many friends here," the victim's father, John Kercher, said in the letter. "She would be proud and happy of what you are doing in her name."