Well, that child did not open the locked door and quietly close the door behind him. And he did not walk to the park and lay down.
So if the dad didn't do it, how come he's not screaming to the media about who had a key and if there was anyone in the apartment with him that night?
Either dad did it, accidentally or on purpose, or someone with access to the apartment did it, imho.
Well the landlord, building owner and/or property management company would most likely have a key to the apartment. I am not claiming that anyone that has to do with/has a connection to any of those entities had anything to do with this child's disappearance, I am just throwing out ideas of who else might have a key to the apartment. Since so far authorities have said there was no sign of forced entry into the apartment. I am sure the police have already thought of that though.
If someone took the kid from the apartment I would think it would have had to be someone he knew though or else he would have screamed and the dad would have heard him. It is unlikely that if he was taken from the apartment that whoever took him got him all the way outside and into a get away car or "carriage" without him waking up.