We cut open the concrete and lured him out with Fancy Feast. Once out and settled he was very docile. Definitely not a feral cat. He is now resting comfortably at the Lange Foundation, an organization for animal rescue. (Feel free to make a donation. :) )
After the building owner saw those photos of the cat under the concrete, he was completely
on board with the rescue operation. After he finally heard the cat meow through the gap in the concrete, he was extremely apologetic for not believing me when I first told him about the situation. He certainly didn't do this on purpose.
And just so you know, the concrete was to be cut open in the near future to gain access to plumbing. These events just stepped up the schedule.
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