Proceed through the metal detector and exit the checkout zone. Ready your shotgun - you will have an encounter with three different monsters. A Juggernaut has a Stabber and Brawler on his leash, and then unleashes them on you. A good strategy is to enter one of the empty jail cells near you and use it as a small fort, killing the monsters one by one as they attack you.

After this encounter, proceed down the main hall. Search the prison cells for any useful items. There is a note in one of them:

By the time you read this, I will be gone. I wasn't sent here with a life sentence, but this is what it's come to. The days here are eternal... relentless. Each new sunrise brings endless boredom and monotony - each new sunset, pain, and fear. I have done my time and I no longer wish to be here.
But I've found a way out. Soon I will be dead, but I am finally free.
I'm coming baby.

Another cell has a fire axe, which you should pick up.

After you are done exploring the area, head south towards the workshops area. Examine the workshop room through the bars. On the other side of the wall there is a keypad. This is a PUZZLE.

To the south, there is a sick bay. Break the barricade and search the room for any useful items, including a first aid kit. Enter the workshop through another door to the south. There is a first aid kit on one of the shelves.

IMPORTANT: Do NOT Turn on any of the machines.

There are several buttons in this room. These activate various machines that make a lot of noise and draw attention, so you want to make sure they are turned off. If kept on for too long, monsters will show up. If any machine turns on, turn it off IMMEDIATELY.

There is another first aid kit in the adjacent workshop.

Keep exploring the workshops. You fins a mystery item, a Work Release Program Application from Ryall State Prison, with a note from Frank that this might be good for you.

Head north to another small room. there is a mystery note: prisoner's letter there:

Babe,
Don't got much time to write today. Just want you to know everything worked out. By the time you read this, I'll be on my way. I am finally gonna be free of this shit hole and all these bastards. It's almost done, babe, and then me and you can be together again like we always wanted, almost.
Love forever,
-R

Pick up the forensic flashlight and follow the footsteps.

WORKSHOP KEYPAD PUZZLE SOLUTION

Downpour Workshop Keypad Puzzle Solution

As you follow the footsteps, point your forensic flashlight around you, including up towards the ceiling. Your goal is to find the five numbers that make up the code to the workshop area keypad. (On easy there will be only for digits). The first number, shown on the ceiling, is a "2". Continue to some license plates billboard and find another "2".  as you keep following the footprints, you will run into the next numbers. Move a hidden box to discover the number "3" behind on the wall. Then for the next number, you will have to activate the machine until it hits the dangling license plate, revealing the number "4". The last number, "5", is to the south on the wall.

WORKSHOP KEYPAD UNLOCK COMBINATION EASY - 2345
WORKSHOP KEYPAD UNLOCK CODE NORMAL AND HARD - 22345

Enter the code to unlock the door, and cross over to the next area.