Rome, Italy (CNN) -- American student Amanda Knox's appeal of her conviction for murdering her roommate in Italy will begin in October, a lawyer for Knox told CNN on Wednesday.
"It's very hard for her; it's her third summer in which she is just waiting," lawyer Maria Del Grosso said. "She is stressed. She is studying but yet she has a lot of time to think and get depressed."
Knox was sentenced in December to 26 years in prison for the murder of British exchange student Meredith Kercher.
An exact date has not yet been set for the appeal to begin, Del Grosso said.
Knox and her parents also face separate trials in October on charges of defaming Italian police, the lawyer said. Knox's trial, to begin October 1, involves her allegations that police mistreated her in custody. Her parents will go on trial October 19 for repeating Knox's allegations.
Kercher, 21, was found semi-naked with her throat slashed in the house she shared with Knox in November 2007.
Knox, 22, and her Italian former boyfriend, Raffaele Sollecito, 26, were found guilty in December 2009 of Kercher's murder. Sollecito is serving a 25-year sentence.
A third person, Rudy Guede, a drifter originally from the Ivory Coast, was tried separately and is serving a 16-year prison sentence.