(ANSA) - Florence, December 16 - Amanda Knox and Raffaele Sollecito, accused in the murder of British student Meredith Kercher, were in the grip of a "murderous rage" fuelled by illegal drugs and alcohol, a lawyer for the victim's family said Monday. Knox, Sollecito and a third person definitively convicted of the crime, Rudy Guede, had "no inhibitions" because of the drugs and alcohol they ingested before murdering Kercher in November 2007, charged Vieri Fabiani. Only later did the "fear take over" and led to false explanations including a simulated break-in and robbery, and a false accusation against a bar owner in Perugia, where the murder occurred, added Fabiani. A Florence court is trying the case against Knox and Sollecito, who have been on trial twice before for the murder of Kercher. Both have said they are not guilty of the accusations. Guede was convicted in a fast-track trial and is serving a 16-year sentence in the murder, but Italy's top appeal court said it was unlikely he acted alone. Knox, who is in the United States and has not returned for this trial, and Sollecito each served two years in prison after a lower court convicted them of murder in 2009. An appeal court overturned those convictions in 2011 and in March, Italy's highest court sent the case back to the appeals stage over aspects of the evidence it argued had not been properly examined before. The supreme court ruled that the initial forensic evidence had been wrongly dismissed in the acquittal and a prosecution theory about a sex game that went wrong should be re-examined. Kercher, 21, was found dead on the floor of an apartment she shared with Knox on November 2, 2007. Guede's DNA was found inside Kercher, on her clothes, and elsewhere in the apartment. Fabiani said that a motive for the murder was "irrelevant" because the crime was committed while the trio were abusing substances. An Italian prosecutor has requested a 26-year prison term for Knox and Sollecito for the murder, plus a further four years for Knox for allegedly slandering bar owner Patrick Lumumba, whom she initially implicated during tough police questioning before later retracting, saying she had been confused. The new trial opened in Florence in September, and a decision is expected on January 10.