Thank you for the replies and welcome. It seems there has been little consideration of this perspective, which I offer here solely as an alternative way to weigh and analyze the available information about the case. There has seemingly been an automatic assumption that either both parents are culpable and aware (yes John, including in Amaral's theory) whether actively or by way of a "pact", or both are innocent. I personally see nothing in the available evidence that compels either conclusion, or excludes the possibility one is innocent and one is not.
What interests me is to go back through the case and ask if removing this assumption of "both in or both out" alters how we might weigh and analyze the available evidence, such as it is. I have already cited the example of how some view the McCanns sustained efforts over the years to keep the case active as supportive of their innocence. Others often refer to how implausible it would be for both to go out for dinner with friends and behave seemingly normally. Do those conclusions change if we consider a scenario in which only one was hiding something and the other was perfectly innocent?
What about if we read one parent's witness statement as factual and the other as not? Does this advance our understanding of what may have happened? Does it open up new possibilities?
Perhaps, perhaps not. I can say I have had cases in which the mystery which evolved was caused by a primary motivation to conceal something from family members, not from law enforcement. Sometimes the deception is not about something criminal,but other types of problems or personal issues.
I am not concerned that advancing a different perspective from which to view various theoretical explanations for the available evidence is libellous. Everything I say is premised on my belief there is presently insufficient evidence (at least in the public domain) to make any definitive conclusion on this terribly sad case.
I live in a jurisdiction in which fair comment is a fairly broad defense to libel but studied in the UK and believe such discussion is well within the ambit of your law. I think it is a shame this would inhibit full discussion of possible ways to analyze the official information available from the various police inquiries, provided of course those doing so have no malicious intent (and I do not see that on this forum). I do not advance the above as a truthful or even terribly likely explanation for what happened to Madeleine--or at least, no more likely than abduction or accident in which neither parent played any role whatsoever.