When I was in living in Australia there was a similar case about Azaria Chamberlain. Lindy Chamberlain was pilloried in the press and was eventually found guilty of killing her baby (she claims a dingo took it).
Due to bungling forensics she was tried and found guilty of murder. She was sent to prison for life. It eventually transpired that she was totally innocent of the crime and the baby had been taken by a dingo.
In my opinion it's impossible for KM to have hidden Maddie for a month and then taken her in a hire car under the scrutiny of the World and buried her. You wouldn't need a sniffer dog to find her after a month in hot weather!
The most likely scenario is that Maddie woke up and wandered off and was taken and killed by persons unknown. The rest is just speculation and bad forensics. Even the Portuguese detectives call the leader of the investigation Inspector Clueless. It's just a media witch hunt, just like the Azaria case.
Google for it and you'll see what I mean.