User blog comment:Speculation no Kyojin/Episode 25 - The Titan in the wall/@comment-3118594-20130930004617

Interesting. Of course, when I read both walls of texts, I came to the conclusion at the time that maybe the miner got devoured by a wall titan. How that happens is left to our imaginations, though; obviously the wall titans can't move like other titans who aren't confined to such tight spaces.

If the miner didn't get devoured, maybe he got squished. Maybe the miner discovered what the walls truly were (they held titans), but at the moment of discovery he lost his life somehow.....though the walls of texts don't state explicitly that the miner(s) died, just that they were never heard from again.