On Saturday morning there was a grey cat lying on the pavement outside
our apartment complex, obviously well-beyond any need of help...

There's a big grey cat name Katzu who lives downstairs in our
building, and he's been known to escape the apartment occasionally...
the cat on the road didn't look quite like him, but the resemblance
was close enough to worry me, especially since I didn't see Katzu in
his window for four days (and he's usually lying in the sun on the
sill for at least part of the day EVERY day!)  But then there he was
yesterday afternoon in all his glory. So the poor dead stranger was a
stranger indeed...