Maddie is dead, even Kate believed she was dead, hence why she told the interpreter that her body was being hidden and concealed in the drain down by the viewpoint...
If Kate is aware that Maddy is dead why prolong the issue as they have done. Best thing would be to go away quietly since they would have nothing to gain.
The McCann's obviously don't believe this for a minute contrary to what you state Mike on the basis of what some Portuguese interpreter was supposed to have heard. I am well versed in relation to Portuguese and Spanish interpreting and I certainly would not trust anything which is interpreted as being anywhere near to the meaning to that originally stated. Many English words have no equivalent in Portuguese and Spanish which means that interpreters have to compensate by introducing words which are alien to the original comment.
Kate probably said that if she is dead she could be in a drain or something to that effect, the possibilities are boundless.
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Kate did say that Maddie was dead, and she told the police interpreter that her body would be found in the drain near the viewpoint - see Amarrals book for confirmation...
The Portuguese police searched the very drain that Kate told the interpreter about soon after she disclosed this information...
The interpreter spoke very good English and would have had no problem interpreting what Kate said to him - as far as I know, when Kate spoke to the interpreter, she did not speak in Portuguese tongue, but plain English...
I can't see how the interpreter misunderstood anything that Kate told him, if she spoke the words in simple and straight forward English, and the interpreter could speak English fluently...
"Maddie is dead, and her body is in the drain down near the viewpoint" - what more could Kate have said that could have been so misleading to the interpreter?
The interpreter said that Kate was very distressed when she called him on the telephone and started to speak to him about these matters...