Where is the key to get out of the Catacombs in Hatred Symbolized?

I think this may actually be a bug in my game but I want to make sure that I'm not missing something.

I have finished the Hatred Symbolized quest in Chapter 2 of The Witcher 2 following Roche's path. I am in the Catacombs where I meet Saskia and Zoltan. Saskia gives me the sword I need to complete the quest. There is a locked door behind them that I should be able to access at this point.

I looted the corpse in the main room and received a catacomb key. I have tried the door after acquiring this key and it still says it's locked. Should this key unlock that door or is there another key that I missed along the way? If so, what is the catacomb key actually for?

This is the path to the Saskia and Zoltan, what you have to do is just go back the same way.

The door behind them is used for Vergen Besieged

An acquired key is for the door marked with 7, really not sure why there is a door protecting a few monsters.

Other marks:

• 1 Pontar Valley
• 2 Bullvore
• 3 Zoltan and Saskia – connected with Hatred Symbolized.
• 4 Adam Pangratt and the mercenaries – connected with Vergen Besieged.
• 5 Dethmold and Adam Pangratt – connected with Vergen Besieged.
• 6 Vergen exit – accessible only during Vergen Besieged.
• ! Nekkers, Rotfiends