Sector 3 is the location of the Biological Research Facility for biomedical research and canine neurological research labs. Mr. Nadira has been conducting mind control experiments and experimenting on the demon dogs. You can also access a vendor machine with the following items:
10x Hal. Cans
From the start room, head through the door to the south. There is another door leading south, but a security lockdown is in effect and the door is locked.
Go through the door to the west and talk to the civilian. He will give you the code to the locked door (5551)
Use the computer console to unlock the door and head through.
Follow the corridor along to the east. There is a computer console on the wall. Use this to talk to Dr. Guerard.
Guerard tells you to ignore the next door to the right (leading north). Ignore him and go through this door.