I saw this cat yesterday when I went for mediation in the afternoon. Apparently he likes to sleep on the neighbours' chairs outside which does bother them. He's so friendly though that if you walk right up to him, he doesn't react - which isn't a good thing for a community cat!
The complainant had said that a cat jumped into her flat the night before Chinese New Year so I walked to every unit above and below hers to ask if they had seen any cats. I also spoke to other residents in the block. None of those I had spoken to had seen a cat nor did they know of anyone who fed cats up there. Of course there were a few cat owners but at least one of them was very responsible with the door covered up. As he pointed out to me, he didn't want his cat to be hurt while it was running around outside either.
The block was fairly new so not everyone has moved in yet. I called the complainant and she seemed fairly satisfied that something had been done.
The best news was that as I was leaving, I bumped into a woman at the mailbox and was asking her about the cats. She asked if there was anyway she could help and she has now offered to mediate!