American Amanda Knox, 22, and her former boyfriend Raffaele Sollecito, 26, are on trial for sexual assault and murder. Kercher's bloody body was found on Nov. 2, 2007, under a duvet on the floor of the apartment she shared with Knox.

Both deny the charges.

Public Prosecutor Giuliano Mignini's summation Friday was expected to last more than six hours, after which a representative from his office planned to go over the technical side of the case, including scientific and forensic evidence.

That presentation was to continue Saturday, after which Mignini will finish his argument and announce what sentence he thinks Knox and Sollecito should receive.

Knox and Sollecito were in court Friday without their parents.

Before delivering his summation Friday, Mignini said it is time to wrap up the long debate over the case, which he called unique in the Italian judiciary. He criticized attacks on the forensic work, saying investigators carried out their jobs professionally.

Criticism of the forensics created an almost parallel trial, he said, but "there is only one trial and it takes place here."

The discovery of Kercher's body with a knife wound to her neck immediately thrust Knox and Sollecito into the spotlight. Prosecutors said 21-year-old Kercher died in a "drug-fueled sex game" the night before with Knox and two men.

Police arrested Knox and Sollecito soon after, along with Ivory Coast native Rudy Guede. Guede opted for a separate, fast-track trial and was convicted of murder and attempted sexual assault in October 2008.

The court sentenced Guede to 30 years in prison; he launched an appeal of the verdict this week.

The key piece of evidence against Knox is a 6 1/2-inch kitchen knife that prosecutors say was used to slit Kercher's throat. The knife belonged to Sollecito and was found at his apartment with Knox's DNA on the handle and Kercher's DNA on the blade, according to a source close to the prosecution who did not want to be identified discussing an ongoing case.

Kercher had never been to Sollecito's apartment and wouldn't have come in contact with the knife, which shows it played a role in the murder, the source said.

Experts testifying for the defense, however, say there is no way the knife could be the murder weapon, because it wouldn't have made the wounds on Kercher's body.

Anne Bremner, a lawyer and former prosecutor working with the group Friends of Amanda, told CNN the knife had been improperly handled by investigators, leading to questions about the validity of the DNA evidence.

Another defense expert, geneticist and private coroner Sarah Gino, testified that the DNA sample on the knife was too small to be definitive.

On the night Kercher was killed, Knox and Sollecito say, they were at his house watching a movie and smoking marijuana.

Their recollection of events, they admitted, was hazy from the drugs, but both swore they went back to the house the next morning. Knox said she could not gain entry, so she called police.

Prosecutors also pointed to what they say is a confession by Knox -- but Knox later said any apparent admission that she was at the scene was made when investigators told her to imagine what she might have seen had she been there.

The argument became moot when a higher court ruled the alleged confession could not be used because the statement was made without an attorney or translator present.

Bremner says the case against Knox is filled with flawed forensics. She said Kercher's bra clasp -- which was found on the floor and contained Sollecito's DNA -- was handled so much that it turned from white to black.

The clasp -- the only evidence that places Sollecito at the scene -- is now tainted, Bremner said.

Crime scene video shows investigators picking up and dropping hairs, not wearing gloves, and throwing evidence aside, Bremner said.

The prosecution source says the crime scene was handled properly.

Kercher had been away from home for only two months when she was killed. The Leeds University student was studying European politics and Italian in Perugia.