A follow up to this issue.
I talked to my neighbours. While they are skeptical about taking
cats on walks, they agreed to check my corridor every now and then
to clear any mess their cat has made.
Indeed! Yesterday, in the evening period before going out for a
run, I noticed a pile of shit at the same spot as always. Not
wanting to create a ruckus then, I proceeded with my run as usual,
and when I come back, viola! Clean spot! Gotta praise my neighbours
on that one!
Not sure of how long this action will last, but for now, I can
say my problems are more or less stopped.
By the way that cat was a persian breed (i think)with cream fur
and a black face and blue eyes. Do not have the chance to take a
picture, but perhaps I'll try to capture one!