Well Registrar, they left the appartment believing the front to be secure.
They were in sight of the rear steps and patio doors which was only 50 metres away and well lit. They were within earshot.
Nobody expects someone to come in and steal their child. I certainly didn't in my back garden which had a side gate to the front, often left unlocked ... and an open back door on the side and out of sight.
You have to admit that it would be hard to find a more sleepy and outwardly safe place than PdL
In her rogatory interview, Fiona Payne says that the McCanns had originally locked the apartment ( as everyone else was doing ) and it was some time later that they decided to leave the patio doors unlocked
She says she can't remember when they made that decision, exactly, but that she remembers having a conversation with Kate about it, and she thinks it was about 'half way through'
Given that they had only been eating at the tapas bar for four nights ( including the one that Madeleine disappeared ) then I guess that suggests the McCanns only started leaving the the apartment unlocked from Tuesday night onwards ( by Fiona Payne's reckoning )
Russell O'Brien, though, in his rogatory interview, says that he checked the McCann children earlier in the week, via the open patio doors, on the first night they ate at the tapas bar ( Sunday ) and that the Mccanns had been 'doing things differently from the word go'
It's all very confusing ... but the indisputable fact is that the McCann children
were left vulnerable in that unsecured apartment ( whether the McCanns had the forsight to realise it or not ) ... the sad outcome is testimony to that