I think you need to start looking out a bit more ... however much you recheck the Tapas timeline ... it won't incriminate anyone there.
How long do you think it takes to enter a ground floor property lift a child and exit?
Particularly if you know the layout of the flat and the sleeping arrangements … for example observation - without the need for inside information - would tell you which bedroom the parents used and which the children you would only need to see which light went on when they retired.
Don't forget allegedly wasting precious time opening a window and raising shutters on the hope that he/she would leave incriminating evidence. A kamikaze abductor

And to top it all, the shutters were tampered with. Would you try to destroy potential evidence before the police arrive? Nothing adds up.
-----------------------------------------------------------------------------------------------------------------
A search was also made for possible biological traces and fibres on the single bed from where the minor disappeared, using a variable-wave light source appropriate for the task, the result obtained having been negative.
The area of the pillow of the bed from the minor disappeared was inspected with the intention to detect the presence of some smell [aroma] characteristic of volatile substances typical of chloroform or ether, this search proving negative.