Raffaele Sollecito and Amanda Knox
09/12/2012 AT 01:45 PM EDT
Amanda Knox's former boyfriend, Raffaele Sollecito, insists in a memoir that he's innocent of murder but acknowledges his memory was impaired by the marijuana that they both smoked and that they later acted in a way that invited police suspicion.
Knox and Sollecito were both released from prison
in 2011 after an Italian appeals court overturned their murder convictions
in the savage 2007 slaying
of Knox's exchange student roommate.
Authorities alleged Meredith Kercher, 21, was killed in Knox's Perugia apartment in a sadistic sex game gone awry. The case featuring the attractive American Knox – she called herself "Foxy Knoxy" on MySpace – became a scandalous sensation in Europe.
In the book Honor Bound
, Sollecito, who is Italian, acknowledges their "odd" behavior when Kercher's body was found, reports the Associated Press
As police investigated the crime scene, Knox and Sollecito reportedly kissed and caressed outside and later at the police station Knox sat in his lap and draped her arms over him.
Sollecito notes in the book they had no "real alibi the night of Nov. 1 except each other" and that during his first night in prison he wavered between "great waves of indignation and a nagging sense of guilt," according to the AP.
Although he insists he was innocent, he was mad at himself for having a bad memory from the marijuana he and Knox smoked the night of the killing, the AP reports.
The book officially comes out Sept. 18, though the AP bought a copy on Tuesday. Knox is writing her own memoir.