Has anyone noticed that it looks like a door in the back of the cell?

I thought it might be a bathroom, but then they always have to let people out to use the bathroom.

So what is that door for?

I looked at a couple episodes, and can't see it well.

Maybe its a secret escape route!!

These sets are apparently easy to build. That's why it is so strange.

Utility room? Closet with roof hatch?

Any other possibilities?

Another thought, the building housing the 12th precinct was supposed to be very old. The door could have been a vestige leftover from a previous remodel and is walled off from the other side.

Its interesting.....It would be nice going to the door and opening it!!

Another thought, the building housing the 12th precinct was supposed to be very old. The door could have been a vestige leftover from a previous remodel and is walled off from the other side.

This theory makes the most sense so far. Sorry for the late reply.