Amanda Knox Case Details: DNA Evidence Analysis of murder weapon may provide new clues.

Amanda Knox Retrial Update: Amanda Knox is back on trial in Florence, Italy, for the 2007 killing of her British roommate Meredith Kercher. The Amanda Knox case hinges on a DNA match on murder weapon. The knife used in the killing will undergo additional DNA testing.

Amanda Knox , 26, who is worried about returning to Italy, where she spent four years behind bars, did not appear court. Both Amanda Knox and her Italian former boyfriend Raffaele Sollecito, 29, insist they are innocent and that their first-grade 2009 convictions were wrongful.

The Italian Supreme Court decided that they still need an Amanda Knox DNA evidence analysis of a miniscule trace of material on the blade of a 12 inch knife that Italian prosecutors claim was used to kill Meredith Kercher. Police found the knife in a kitchen drawer in Sollecito's Perugia apartment in 2007. The evidence is labeled number 36-I.

The Italian Supreme Court decided Amanda Knox and Sollecito's lawyers' requests for further evidence or testimony, like that of the semen stains at the crime scene.

The Amanda Knox appeals trial will be overseen by Judge Alessandro Nencini in Florence.

Amanda Knox DNA evidence analysis of trace 36-I may be inclusive or turn up nothing. To satisfy the forensic science of the Italian Scientific Police, the test would have to be done more than once and reach the same conclusion. But there is not enough trace 36-I. There is only 120 picograms (one pictogram is a trillionth of a gram.) The trace had been ignored before because it was thought too small to be of use. Judge Alessandro Nencini has to decide whether to order Amanda Knox DNA evidence analysis.

Before the trial, Raffaele's father Francesco Sollecito told the Guardian he hoped the court would reopen the case by "360 degrees" and that he was "quite satisfied" by the court's decisions.

None of Kercher's relatives attended the proceedings, but Francesca Maresca, the family's lawyer, said: "We are still convinced of the presence of all three of the defendants at the scene of the crime."

Patrick Lumumba, the who Amanda Knox wrongfully accused of having killing Kercher, said "I say the same thing I said six years ago. I think she is guilty, and that is why she slandered me."

Judge Alessandro Nencini has to decide whether to order Amanda Knox DNA evidence analysis.

Amanda Knox, 25, was convicted of the murder of her British roommate, Meredith Kercher in Perugia, Italy. Amanda Knox spent four years in prison before the conviction was thrown out by an Italian appeals court in 2011. The Italian Supreme Court rejected the Appeals Court ruling in March. Amanda Knox and her ex-boyfriend Raffaele Sollecito, 29, have been ordered a sit for a new trial. The Supreme Court filed its papers on June 18 that said the Supreme Court judges supported the prosecutors' original theory. Prosecutors claimed that Amanda Knox and Sollecito caused Kercher's death during a forced "erotic game" that turned violent. The Supreme Court judges ruled on the Appeals Court process, not the testimony or evidence in the case.