Rome ( CNN ) -- Two inmates testified Saturday that Amanda Knox , the American student convicted of murder in Italy , was not actually involved in the killing of her roommate . But they offered two different accounts on who the actual killers were . Three other inmates testified as well . Knox was sentenced last year to 26 years in prison for the death of Meredith Kercher at a house the two shared in Perugia , the central Italian town where both were students . Knox has vehemently proclaimed her innocence and her family has continued to fight the conviction . Two hours of legal wrangling between attorneys passed before the judge decided to allow inmates Mario Alessi and Luciano Aviello to testify . Alessi is serving a life sentence for kidnapping and killing an 18-month-old boy . Alessi testified that Rudy Guede , who has also been convicted in Kercher 's murder and is serving a 16-year sentence , told him that neither Knox nor her Italian boyfriend at the time , Raffaele Sollecito , were involved in the killing . Later in the day , Aviello , who has ties to the Naples Mafia , testified that it was his brother who was the killer , together with an Albanian man . According to Alessi , Guede said that he and an unnamed friend visited Kercher to try to get her to participate in sexual acts . When Kercher denied them , Guede 's friend forced himself on her , and Guede also participated , Alessi said . At one point , the friend pulled out a knife , and then Guede , who was holding Kercher at the time , noticed she had started bleeding , Alessi testified . Alessi told the court that Guede tried to stop the bleeding , but that his friend urged him to leave . `` We need to finish her otherwise she will tell on us , '' Alessi quoted the friend as telling Guede . The friend then proceeded to inflict another wound on her , Alessi testified . Alessi said Guede remained by himself with Kercher for a while , but eventually left her injured . Prosecutors and the lawyer for Kercher 's family questioned the validity of Alessi 's testimony . Through his lawyers , Guede denied Alessi 's version of events . During his testimony , Aviello gave a different account . Aviello said that on the night of the killing , his brother came home with scratches and other wounds . As Aviello tended to the wounds , his brother confessed to him that he had killed Kercher , he said . According to Aviello , his brother said that he and an Albanian man entered the residence to steal a painting , and in the act ended up killing the girl . Aviello said he has n't seen his brother in three years . `` Inside me I know that a miscarriage of justice has taken place , '' Aviello said of Knox and Sollecito 's conviction . Prosecutors questioned his credibility and Aviello admitted that he has been convicted of defamation seven times . The appeals process will continue June 27 , when Guede is expected to testify . In an additional twist Saturday , another inmate who the defense put on the stand to verify Alessi 's version of events , testified that he , in fact , did not know anything about who carried out the killings . Even though his cell was adjacent to Alessi 's and Guede 's , the inmate was Romanian and did n't know what they discussed , he said . Another witness Saturday was Marco Castelluccio , a Mafia member who testified from behind a screen because he is a protected witness . Castelluccio said that he also heard from Guede that Knox had nothing to do with the crime . Kercher , 21 , was found dead on November 2 , 2007 , seminaked with her throat slashed . Knox and Sollecito were both found guilty of the murder . Knox was sentenced in December 2009 . Guede , a drifter originally from Ivory Coast , was tried separately . As part of her appeal , forensic experts are retesting evidence that was used to convict Knox . That evidence includes a knife found in Sollecito 's apartment with Knox 's DNA on the handle and what Perugia prosecutors say is Kercher 's DNA in a tiny groove on the blade . The prosecution contends that the knife was used to stab Kercher in the neck and that it had been cleaned . The DNA matter attributed to Kercher consists of flesh , not blood , they say . The sample , however , was so small that forensic scientists investigating Kercher 's murder were not able to double-test it in accordance with international forensic science norms , which Knox 's legal team says raises doubts about its validity . The second piece of evidence the forensic experts are testing is the tiny metal clasp from Kercher 's bra , which was cut from her body after her slaying . Forensic scientists in the investigatory phase determined that Sollecito 's DNA is present on the metal clasp . The clasp was identified on an investigatory video the same day Kercher 's body was found . But it was not collected until nearly six weeks later , giving the defense cause to question whether the sample may have been contaminated .
Inmates tell different versions of who was behind killing . A total of five inmates testified Saturday . Knox was convicted of murder in the death of her roommate . The group of convicts include a child murderer and a Mafia boss .