I have never fully understood the locking of the main front door. Despite years of trying. IMHO it was a slam lock, probably with a latch\lever on the inside to dead lock, remember the old fashioned Yale type locks.
But it would also be DEADLOCKED from outside, if you read JT's Roggie statement she describes locking the door so her daughter could NOT get *out.
There are so many locks and lever systems, and I really have no idea what types they use in Portugal.
Therefore the status of the front door was locked so no one unless they had a key could get IN. But anyone could get *OUT. The door could afteral, only be deadlocked from outside (i.e. turn the barrel twice)
Therefore it would have been IMHO very possible for an abductor to have entered via the rear sliding & unlocked patio door and mere WALKED OUT OF THE FRONT main door.
Then!!
Of course, begs the question
What's with the shutters and windows.
A Break in: And for convenience of the conversation, as fully explained in the Sun Times, ''Beyond the smears'' The cleaners were in the habit of leaving the windows unlocked. That explains no broken glass
A Break out: Really, with a door you can walk through!