ROME -

Amanda Knox's lawyers have formally asked Italy's court of last resort to review the Seattle student's appeals court conviction for the 2007 murder of her British roommate.

Defense lawyer Luciano Ghirga said the paperwork was submitted last Thursday to the Rome-based Court of Cassation.

Knox's lawyers had pledged to turn to Italy's top criminal court after a Florence appeals court in January reinstated a lower court's murder convictions of Knox and her Italian former boyfriend Raffaele Sollecito.

The appeals court concluded that Knox and Sollecito are guilty in the 2007 murder of Knox's former roommate Meredith Kercher in Perugia, Italy, where all three were studying. 

The defense filed its case after studying the appeals court's written rationale, issued in April, for the convictions.

Cassation judges can either uphold the convictions if they find the appeals trial was properly conducted or order yet another appellate trial.

Knox's defense team has previously said that DNA evidence at the scene was mishandled by investigators and that knife wounds on Kercher's body did not match the supposed murder weapon.