Amanda Knox Has "Nothing To Hide"

For five months, 21-year-old Amanda Knox has sat silently in an Italian courtroom accused of murder. On Friday, her silence will be broken as she takes the stand to defend herself against the charges.

Knox went to Italy to study abroad for one year. Whether she ever makes it home could rest on her testimony in court.

"She has nothing to hide," Knox's father, Curt, told CBS' The Early Show Thursday.

Knox, a Seattle native and former University of Washington student, has insisted she was not home during the slaying of her British roommate, Meredith Kercher, back in November 2007 in Perugia, after initially giving conflicting statements.

Curt Knox, who spoke to The Early Show shortly after visiting Amanda in prison, described his daughter as nervous, but confident about her testimony. Knox added his daughter would speak Italian during the trial. "She doesn't want anything misinterpreted," he said.

Prosecutors allege Kercher died during what began as a sex game and are seeking conviction on murder charges of Knox, and Knox's former boyfriend, Raffaele Sollecito, an Italian. The two deny wrongdoing.

After a 14-hour interrogation, Knox signed a letter implicating herself in the crime. She described that experience in an audio tape obtained exclusively by CBS News.

"They threatened that I was going to go in prison for 30 years because I was hiding something," Knox is heard saying on the tape.

Curt Knox, however, said he has "100 percent faith in the judicial system" and that the court will find his daughter innocent.

Last week, the court heard emotional testimony from the victim's family. Fighting back tears, her mother, Arline Kercher, said the family will "never get over" the brutal murder.

Knox looked on as the victim's relatives took the stand, and one of her lawyers, Luciano Ghirga, said afterward she was "very moved" as she listened to the Kerchers' testimony. Knox's lawyers chose not to cross-examine any of them.

Kercher was found in a pool of blood in the apartment she shared with Knox. Prosecutors said Sollecito was holding her by the shoulders from behind while Knox touched her with the point of a knife.

The two, jailed since November 2007, are charged with murder and sexual assault. If convicted, they could face life imprisonment, Italy's stiffest punishment.

Sollecito, 25, has said he was at his own apartment in Perugia, working at his computer. He said he does not remember if Knox spent the whole night with him or just part of it. As he left the courtroom after the Kerchers' testimony, he said, turning toward the cameras, "I expect justice, just like them."

The victim's father, John Kercher, said she complained about Knox's bathroom habits. She also expressed surprise that Knox had hooked up with a boyfriend shortly after her arrival, he said.

Kercher was also described as a physically strong person, who exercised and studied karate.

"She could have put out quite a fight," John Kercher said, responding to a prosecutor's question of his daughter would have defended herself if she could have.

The Kercher family has joined the criminal trial as civil plaintiffs.