I'm with the neighbour. Too many prossies pick stupid locations and crap apartments because they are cheap. They need to have a bit of common sense about it. Ground floor always, and if possible, not with a communal corridor access. House is better, like a terraced. They also gravitate to places with no parking. In Bristol, the number of times I have been late because they are in some stupid apartment with no parking, on a one way system.
Most of these new build apartment blocks and conversions are shite, so that bloke and his missus will be hearing the creaks and groans all day of people traipsing up the stairs, and then the bang bang bang of shagging all day. To make things worse, he's hearing that and looking at his old hag of a wife getting jealous.
Prossies.... put a bit of thought and care into your location.
If it were me on the stairs getting confronted though, I would say "police business. Please go back inside. Theres been a murder. Stay inside until we tell you its OK to come out"