Sollecito said the thought of Knox as a killer was "impossible"
Raffaele Sollecito, 25, is beginning his 25-year sentence for the murder of British exchange student Meredith Kercher in her flat in Perugia, Italy, in 2007.
From the start of the highly publicised case, Knox was the primary focus of media attention, leaving Sollecito a somewhat shadowy figure in the background.
But who is Raffaele Sollecito, and how did a nice middle-class Italian boy come to be involved in an internationally notorious murder?
According to a letter that Sollecito wrote to an Italian magazine, the pair met at a concert just two weeks before the murder.
They became an item. Although from different countries, Knox and Sollecito appear to come from similar comfortable, middle-class backgrounds.
Sollecito's family - his father is a urologist - was wealthy enough to buy their student son a flat in Perugia.
It is the same flat that Knox now claims she spent the night in when Miss Kercher was murdered - reports of her initial statement to police originally placed her at the scene of the crime.
In letters from his jail cell, he wrote: "The Amanda I know... lives a carefree life."
"Her only thought is the pursuit of pleasure," wrote Sollecito to his father.
"But," he adds, "even the thought that she could be a killer is impossible for me."
Neither of their cases were helped by CCTV evidence that found its way into the Italian press, reportedly showing the pair buying sexy underwear together two days after Miss Kercher's death.
Fondness for marijuana
Sollecito, who is from the southern Italian city of Giovinazzo, has blamed himself for making a "trap" with his own hands.
His defence was that on the night of the murder he was at home surfing the internet - although police say his computer records do not support this.
He has also admitted smoking marijuana at the time. Both Sollecito and Knox admitted a fondness for the drug - which they blamed for their inability to recall their movements on the night Miss Kercher died.
In a letter to an Italian magazine he wrote: "One morning you return to her house and find a big mess.
"The problems begin: the police arrive, break down the locked door to a bedroom and discover the lifeless body of one of her (Amanda's) friends.
"From then on they suspect everyone and everything."
To his father he promised: "Dad, I will never smoke another joint in my life."
Sollecito now faces the prospect of 25 years behind bars for the crime that brought the international spotlight on Perugia and a small group of students.