Up on the second floor's balcony, toward the back of the map. This is a really fast check if you spawn on the second floor, in the commander's room.

This is the commander's room. It'll be the first room on the second floor (to your right) if you're coming up the stairs from the side not blocked by the electronic gate. From inside here, facing the door, the balcony check above will be directly in front of you.

The “men's” room. This is just down the stairs from the commander's room. It's the door to the right in the middle of the hallway toward the electronic gate.

The cell. This is the cell that Roy Campbell is in when you start the main game. To reach it, either a guard has to open it, or you have to crawl all the way around through the vent in the bottom picture, which is in the next cell over.

This is probably the last location you'll check; this is the exit point from the mission in the main game, and the furthest one away. More often than not, you'll likely spawn here, meaning the exit won't spawn here if that's the case.