The Amanda Knox appeal trial just took a remarkable turn.

Independent, court-appointed experts told the Italian court that DNA evidence was not conclusive, and could have been tainted during the investigation.

During the initial police probe, Knox's DNA was found on the murder weapon - a bloody knife. Additionally, DNA of Knox's then-boyfriend Raffaele Sollecito was found on a bra clasp belonging to murdered British student Meredith Kercher. Like Knox, Sollecito was also convicted of Kercher's murder.

The international procedures for inspection, protocol and collection of evidence were not followed for both the bra clasp and the knife, the experts testified.

One cannot exclude that the results obtained could have derived from phenomena of environmental contamination and/or contamination, which could have taken place in any of the phases of the evidence gathering and/or manipulation.

The news could be the biggest break yet in the Amanda Knox case. Prosecutors primarily relied on the DNA for proof that Knox and Sollecito were involved in the murder. The court will discuss the findings over the next few weeks.

In 2009, Knox was convicted of the murder of Meredith Kercher, who was found stabbed to death in the house she shared with Knox in the Italian university town of Perugia. The court ruled that Knox andSollecito slit Kercher's throat in a possible drug-fuelled sexual assault. Knox and Sollecito were sentenced to 25 and 26 year prison sentences for the crime, respectively.

Click here to see photos from the Amanda Knox trial.