Again you miss the point ,if you are in a hole babbling and being nervous means you only keep digging and add to your woes.
This story if rubbish is easily cross checked.
If you use such a story you need to have a Mick in Apartment 4 who will say he is your friend .
If your are stopped and questioned there will often be two individuals.One can easily go and check such a story.Also do not overlook the the ubiquity of CCTV these days .
As I said you may be at a point where you are minimising your damage and imaginary stories and imaginary friends in imaginary apartments are not going to add to your situation.
Too much waffling you are more likely to incriminate yourself or get caught out with some cock and bull story.
Keeping your mouth shut it is up to them to provide proof.Entry into an apartment buiding is proof of nothing other than entering a building,entry to an apartment is proof of nothing either.If guards wish to initiate a prosecution a file has to go to DPP's office.They will only initiate a court case if they think they are likely to win.It then goes before a judge who has to decide on it ,at this stage someone should have legal advice and representation.
Admitting nothing,not providing a statement or signing a statement is the way to go.
Otherwise you will be likely be steered by questioning police into admitting some sort of guilt and their job will be done .Case closed.You will have become one the feathers in their cap and positive result that shows their superiors ,politicians and others that they are implementing the law.
Keep your yip yap on phones and in texts non-descriptional and general while you're at it.