June 9, 2010 -- A jailed Italian man claims in a legal deposition that convicted killer Amanda Knox is innocent, and accuses his own brother of killing Knox's roommate Meredith Kercher, Knox's legal team told ABC News.
Luciano Aviello, who is tied to the Italian Mafia and currently serving a 17 year prison sentence, told Knox's lawyers in a video-taped prison interview in March that his brother Antonio showed up at his house in Perugia wearing a bloodstained jacket the night of Nov. 1, 2007, the night that Kercher was murdered.
Aviello claims his brother told him that he broke into a house and killed a woman.
Antonio Aviello then asked his brother to hide the bloody knife and the keys to the Perugia apartment where Kercher and Knox lived, he claimed in the deposition.
"I hid everything under a little wall behind my house and covered it with soil and stones. I am happy to stand up in court and confirm all this and wrote to the court several times to tell them, but was never questioned," Luciano Aviello said.
Knox's legal team told ABC News, "The alleged location of the murder weapon and the keys to Kercher's house has yet to be investigated, and we hope the court will look into it."
The Italian magazine Oggi quoted Luciano Aviello as saying he had his brother move to Perugia because of trouble in their hometown of Secondigliano.
While in Perugia, Antonio Aviello and another man were hired to steal some paintings from a home, but ended up the apartment shared by Knox and Kercher because they were either given a wrong address or bad directions, Luciano Aviello claims according to the magazine.
Kercher allegedly died in a struggle with the two men, the convict said.
The inmate said he first wrote to the Perugian court in June 2009 while Knox and her ex-boyfriend Raffaele Sollecito were on trial. Aviello wrote two more letters to presiding Judge Giancarlo Massei in July and September 2009.
Aviello was never looked at as a witness or called to testify, although prosecutors did have a homeless man testify and tracked down potential witnesses who were mentioned in press reports.
The Knox team has included their interview with Aviello as a part of their appeal filed in April seeking to overturn Knox's conviction.
Knox and Sollecito were convicted of murdering Kercher last year, and Knox was sentenced to 26 years in prison.
Prosecutor Giuliano Mignini told ABC News that his office will look into the matter as soon as possible.
"We must always verify what is presented to us," Mignini said.
New Hope for Amanda Knox Appeal
Knox was back in court last month to face the possibility of being charged with slander for stating during her trial the Perugia police struck her on the head during their interrogation of her in the wake of the murder.
A third man, Rudy Guede, has also been convicted of taking part in the murder and is serving a 16 year prison sentence.
It's not the first time that someone has claimed to know who the "real" killer was.
Convicted child murderer Mario Alessi, who was held for a while in the same prison ward as Guede, claimed that Guede confided in him that Knox and Sollecito were not at the house when Kercher was killed. Alessi claimed that Kercher was slain by unnamed friend of Guede.
Prosecutors questioned Alessi, and nothing came of his allegations.
Knox's lawyer told ABC News, "She knows she is innocent, but is waiting for the day she is believed."
ABC News Ann Wise and Phoebe Natanson contributed to this report