Cite? Who has often portrayed her as a "criminal mastermind"?
Well, I suppose it's a reasonable (if possibly slightly hyperbolised) deduction that could be made from comparing observations of AK's known behaviour with a presumption that she committed the murder.
After, all, if Amanda Knox
was involved in the murder, then the following chain of events would most likely have taken place:
1) She was involved in the brutal and bloody murder of her housemate between 9.30-11.30pm on the 1st November 2007.
2) She then had the wherewithal and cunning to not just clean up the murder house extensively that same night (while strangely leaving the actual murder room largely untouched), but to also
deliberately leave some blood evidence in the bathroom - evidence which she must have known might be incriminating to her and/or her boyfriend.
3) In the midst of this, she had the cunning to try to misdirect police by staging a break-in - figuring that this might convince the police that the crime had been committed by a stranger-intruder.
4) Instead of disappearing back to her boyfriend's flat and lying low (easily the safest option), she deliberately placed herself back into the murder house the following morning - presumably in an act of cunning (but risky) double-bluff to make her appear innocent.
5) Whilst she initially reacted with shock and horror at the discovery of her housemate's murdered body, she then decided to pursue an elaborate double-bluff regarding her later reactions. She would have realised that most killers in her position would almost-certainly try to appear as devastated (if not more so) than everybody else, in order to deflect attention from themselves. Therefore, she decided to consciously draw attention to herself and Sollecito by avoiding the memorial service, by making curt remarks about Meredith's body, and by making suggestive remarks in an underwear shop. This, she might have reasoned, could confuse the police - after all, why would a real culprit take such deliberate actions to stand out from the crowd?
6) After she'd been questioned two or three times already by the police by around the 4th November, she consciously didn't seek the advice of a lawyer, nor did she contact the US Consulate for advice. Having committed the crime (in this scenario), she would obviously have been on the constant lookout for police suspicion of her. However, she instead chose to remain steadfastly clear of legal or Consular assistance. She must have cunningly thought that to seek such assistance might be seen by the police as evidence of culpability - regardless of the very real help that such moves might have given her.
I believe that it's points like these that would require one to consider Amanda Knox as a cunning, clever and manipulative operator - if she was involved in the murder. Perhaps the term "criminal mastermind" might be overdoing it a bit, but I don't think it's all that far wide of the mark...