Perugia, June 28 - Raffaele Sollecito's father said recent comments made by prosecutors in Perugia on the supreme Court of Cassation's decision to order a retrial trial over the 2007 murder of student Meredith Kercher were ''unusual and improper''. In March this year, Italy's highest appeals court scrapped the acquittal Sollecito of his ex-girlfriend Amanda Knox in the case of Kercher's murder in Perugia and ordered a new appeals trial which will be held in Florence as soon as this fall. Knox, now 25, and Sollecito, now 29, both students along with Kercher, were convicted of her murder in 2009 and served almost four years in prison before their convictions were overturned in 2011. Perugia Prosecutor Giovanni Galati earlier this month had said ''the Supreme Court of cassation sentence substantially demolishes the appeals court sentence of Perugia... underlining the incomplete explanations and the constant violations of the law''. Another Perugia prosecutor, Giancarlo Costagliola, said the decision of Italy's supreme Court of Cassation to order a new appeals trial has raised Kercher's parents' hope of finally discovering who killed her. Francesco Sollecito said the Perugia prosecutors should have remained silent as the ''trial is still outstanding'' and the case was no longer theirs.