Hi, and sorry for the cross-posting; I'm just feeling a little desperate
here!

We have 3 cats, all of whom are indoor cats (downtown Manhattan, New York
City, friendly small-ish neighborhood). The only outdoor space they get to
use is the fire escape, which has no roof access. They can climb to the top
of the fire escape in our 4-story building and down to the 2nd, but unless
they jump down (which they have never done -- they're quite complacent and
ultra careful!) that's the extent of their outdoor life.  Usually they just
lie out there and enjoy the sun, and dart back indoors through the window.

Two days ago, one of them -- by far the most agile (but also the most timid
and nervous) simply disappeared. It makes no sense at all. We're in a super
busy street (a loud restaurant directly opposite has outdoor seating and
they routinely sit there and watch the cats for fun, till all hours, so a
cat falling from the 2nd floor wouldn't be missed; also, it's a very busy
pedestrian street, and this happened sometime during the day/evening).
Somebody would certainly have noticed if a cat fell or jumped. At night, we
always close the screens so the cats are indoors.

I'm sure there are those of you who feel that it's wrong to let a cat on a
fire escape, but they've been happily and safely doing this for 2 years.
Perhaps we should rethink this, but this is the cats' oasis of freedom in
the outside world. They ALWAYS come back and stand out there and meow if a
window is closed on one floor (even if they can easily get through an
upper-floor window).

We have posted missing-cat signs all over the neighborhood and have
canvassed the neighborhood; I have the cat on all the online shelter boards
(I get regular emails whenever a remotely similar cat shows up in any of the
boroughs) -- I have checked alleyways, everywhere, nearby parks, etc.

If anybody has any recommendations beyond what we have done, I would be
eternally grateful. I'll be hitting the shelters later this morning.  Oddly
enough, I found a friend's dog last year after 4 days of searching --  
through some weird little website that I almost passed by because it looked
so insignificant. But no such luck yet with our cat.

On a much more sinister note, what happens if a cat is found run over or
something? Is there any kind of registry to check?  I haven't found anything
online, and much as I hope and still believe that we'll find our cat or that
he'll come back any day now, I would want to know if something has happened
to him. Does anybody know what happens when somebody finds a cat who's been
run over (or met some other kind of fate)? It would be pretty awful to
fathom that they'd just be disposed of without some kind of report?

Any help would be much appreciated. The cat is 3 years old and very timid.

Thanks in advance for any advice/answers anybody can provide!