One is either convinced by the below, or automatically sees alternate explanations:
Against the lone-wolf scenariohttp://aklwei.wordpress.com/2011/02/21/the-actual-case-against-amanda-knox-and-raffaele-sollecito/
Both the Micheli report from Guedes trial and the Massei report from Knox/Sollecitos trial rejected the argument that Guede acted alone. There are many reasons for this; chief among them that the argument that this was a break-in was rejected and instead the disarrayed room was staged to make it appear there was a break in. Guede would not have a reason to stage a break-in to deflect attention while at the same time leaving unassailable evidence of his presence, including in the bathroom. Therefore, Guede would have had been provided access to the house, and the Massei report argues that it is improbable that Meredith let Guede in.. therefore whoever let Guede in was at the house that night and was responsible for staging the break-in to deflect attention from themselves. Amanda was the only resident without an provable alibi.
The signs that the burglary was staged include:
No footprints in the grass below the window (and no ground dirt tracked in)
An undisturbed nail sticking out on the outside wall under the window, which seems unlikely if someone pulled their body up over that wall
A lack of scuff marks on the wall that would have been climbed
Glass still sitting on the window sill that a climber would have had to pull themselves over
No glass was found on the ground outside the window
What was disturbed in the bedroom with the break-in was only clothes; boxes and drawers remained closed and unchecked
Valuables, including computer, were not taken
The shutters on the window with the broken glass were argued to be closed; this would have required climbing the wall twice.
Someone breaking in would have to rely on the chance occurrence that the inner shutters were not locked, and thus not preventing access once the window was broken.
