Thought I would make my second post here regarding my theories. Sorry for the length.
Theory 1. The parents did it
I want to speak in general terms because it is possible that it could go both ways....and the details as we know are not always reliable or even known. I believe if the parents or just one of the parents killed Maddie it was an accident/cover-up. Either way I think that it would have to be Gerry that actually took Maddie's life. I think this because:
A. I don't think these are parents with absolutly no love for their children. Yes I think leaving them all alone is very bad neglect but I still don't think they intended to hurt them. To me if they wanted to "get rid" of Maddie there were many other ways to do that through a staged accident or something. Because I believe this, I just can not believe that these parents murdered their child and then went to dinner. Of course they may have but it seems that someone would have noticed something in their personalities.
B. So if she didn't die before dinner then it had to happen between 8:30ish and 10:00ish. Through the statements of the Tapas 9 and the employees at the restaurant Kate never checked on the kids until 10 pm. In fact it was always the fathers that did the checking even on the previous nights. This to me sounds reliable as more then one person apparantly agreed.
Now as to who did it when and how I think the most likely scenario is that Gerry or Gerry and O'brien checked on the McCann children. I don't think Maddie had passed from any previous sedation because they would have had to actually make sure she was breathing when they checked on her. A sleeping child could easily look like a deceased one in a dark room while they are in bed. To me this would mean that possibly she was awake and crying. If O'brien wasn't with Gerry at this point maybe he called O'brien to have him come help him give Maddie a shot or other sedative to put her back to sleep so they could re-join the party.
It is at this point that I think they over-dosed her. This could have been because Kate had previously given her something and they didn't know it or they were drunk and made a mistake. She may have vomitted, choked etc. If this is what happen I think at this point both Gerry and O'brien felt the only way out was a cover-up and they put a plan in action. Either O'brien called Mr. Murat for help or Maddie was hidden in the wheel well of his car. Their decision may have been influenced by the wine but who knows.
I don't believe she died of a violent accident because I think there would have been too much blood to hide that quickly.
I think when Gerry got back to the Tapas bar he had planned (or him and O'brien planned) to have Kate do the next check so that she would find that Maddie was missing. This is common in criminal profiles where the perpetrator will try to get someone else to happen upon the murder or kidnapping to take the heat off of themselves. He could have easily said to Kate, "honey I did the last can you please do this one"...or "Maddie wanted you when I was up there before she fell back asleep so maybe you should check on her". To me the question to Kate would be "why did you check on the kids that last time?" And why at 10:00? Well O'brien returned to the bar around that time...that may have been Gerry's signal to prompt Kate to do the check as O'briens return told Gerry that Maddie was hidden.
If this is how it happened to me most everything makes sense. Kate doesn't know what happened but maybe suspects something. The media campaign would happen because she felt she was really looking for her daughter. Gerry couldn't complain because that would be suspicious. It is of course possible that Kate does know the truth now but I don't think she did at that point.
So where is Madeleine? If the newest news is correct and there has been DNA matching Maddie's found in Murat's villa then I would assume he helped hide her body. But if she was in the wheel well I'm sure she could have safely stayed there for a little while. I haven't been able to find any time-lines of what the Tapas 9 did the day and days after Maddie disappeared. If she was in Murat's villa and transferred to the wheel well or she was in the wheel well all along O'brien could have easily drove off and buried her somewhere within an hour or two I would think.
As far as Kate having the death smell? I think that could easily be explained. If Maddie died in her bed Kate may have layed on it crying for her child. If Maddie had cuddle cat when she died it could have transferred. I think the places the death smell were found (the car) are more unexplainable. Not saying Kate is innocent but I think it would make sense. Heck they could have told her later and she could have held Maddie before "they took her away" for burial/disposal. But to me that doesn't even make much sense. If you were trying to "cover-up" a murder wouldn't you get rid of the clothes and things you had been wearing? As the parents of a "kidnapped" child it doesn't seem like that would be hard to do as no one was suspecting you and by the time they did if the clothes you were wearing couldn't be found it wouldn't be evidence enough to arrest you.
Theory 2. A stranger did abduct her or Murat abducted her
To me this theory is one in the same because I have to ask myself "if she was abducted why?". To me there are only a couple reasons children are abducted. 1. For profit or 2. For their own pleasure (I know that sounds gross).
For either of these reasons Maddie would have made a good "not the best in all scenerios" but still a good target. These families all had very small children and were out every night leaving them alone. Anyone, whether it was someone they knew or not, could have easily seen a pattern should they have been watching. I doubt it was a stranger just because if the person was watching they would have seen that the checks were often and that would have been risky. Plus one couple had a monitor and unless they knew that why would they zero in on Maddie and no one elses child?
I believe if she was abducted it was by someone in the Tapas 9 for profit. Either they co-conspired with Murat or Murat did it himself. The only reason I question the profit scenerio is because regardless of where it came from there WAS a smell of death and who would abduct a child for profit that wasn't alive?
Bottome line in this theory I believe if she was in fact abducted she was abducted by someone that used her and murdered her. Possibly this was arranged by O'brien for a profit. Murat could have paid him to hand over Maddie.
I do find this pretty unlikely because of the death smell being on Kate and the car. Obviously they wouldn't have helped a man that bought their child to fulfill a fantasy unless O'brien was blackmailed or something I don't know why he would help either.
A couple general points before I write a book lol...
-I don't think Maddie was hidden and moved 25 days later or even more then a week later. I think that would have involved too many people to execute.
-I don't think Maddie was kidnapped at least not in the stranger sense of kidnapping because a lot of the facts wouldn't make sense but I'm sure there is a small possibility.
-I don't think the kiddos were all in the same room because I don't know why the parents would all arrive at such different times to the bar. As well as the fact that one couple had a monitor. Of course it is possible SOME of the kids were in the same room which would lead to more ifs.
-I definatly don't believe the majority of the Tapas 9 know what happened but if they aren't already they are probably becoming suspicious.
Whew I know a lot of this has been covered but I had to write it out for my own thought process.