I find it difficult to imagine that anybody set on suicide will choose a stairwell.
Such an odd place for a suicide ... and such a good place for a hit. Easy to keep under complete surveillance, no witnesses.
People often choose places where someone will find them, especially if they live alone. You don’t want to be rotting in your apartment for 4 days in the heat before the someone calls the janitor to go check on that smell...
I agree.