The diagram states the window and shutter were the main source of the investigation which imo was nothing more than a big fat red herring.
The abductor entered via the unlocked patio door, opened the front door (that overlooks the car park), opened the shutter and window (to throw everyone), scooped up MM and straight out the front door shutting it behind them and into a waiting car.
The next red herring was the sighting by Jane Tanner which for years everyone thought was MM's abductor carrying her in arms until Dr Totman came forward and said it was him carrying his daughter.
I find it amazing that the PJ did not knock on PF's door on 3rd May asking if she saw or heard anything. She was literally a few meters away, above, when MM was abducted. I think it was former UK police officer, Colin Sutton, who said you always start off clearing the ground beneath your feet before moving on. Sounds very sensible and logical to me.