A bit of modus operandi.
Even if an apartment looks like no-one is home, IMO a burglar may knock at the door just to make sure.
Most times when it looks like no-one is home, there really is no-one home, so the knock goes unanswered, and entry and burgalry commence IMO.
However for this the burglar needs a cover story IMO, just in case he gets surprised and someone does answer the door.
Something simple like "oh sorry I thought the so and so family was staying here".
This may possibly be what happened IMO at the apartment directly above 5G on 16 April 2007 (source: partly casefiles, partly crimewatch). There was a knock at the door, asking for someone who isn't staying there. Soon afterwards those tourists did go out, and the place was burgled.
IMO it is likely that the very first directly relevant physical event on 3 May 2007 at 5A, was that during dinner while the apartment looked and sounded like no-one was home, someone knocked at the north door and got no response.
But that is just one person''s amateur opinion and it is possible it may be wrong.
