General objectives of the stage: Test Facility is the first of three stages of Death Factory mission. Main objectives of this stage are to eliminate Dr. Marcus Green and disable security systems, but before it becomes possible, first you have to enter the main part of the facility.
Move straight ahead. After reaching the fork choose the right corridor and enter the left room. You should see guards questioning a scientist in an adjacent room. You do not have to worry about them because you're standing in front of one-way mirror, so no one can see you. But you have to figure out how to get inside that room and recover stolen files.
The most aggressive option involves using Silverballers to deal with security guards. If you plan to act like this, I recommend using point shooting. After the successful action go through the damaged shutter and collect stolen files.
If you do not want to kill anyone then take a keycard from the room you're in and return to the previous corridor. Use the keycard to unlock the passage shown on the above screen.
Now you can act in two ways. First option is to wait until guards break interrogation for few moments. One of them will appear here (screen above). You have to stun/kill him and put on factory guard disguise. Now enter the interrogation room and collect stolen files, using Instinct when needed.
Another option is to distract guards and this is a better idea because you will not risk too much nor use Instinct. Locate a fire alarm switch shown on the above screen and use it.
Quickly move to a spot shown on the above screen - a counter near the room with guards. Wait until one of them comes out to check the alarm and then quickly enter the room. Collect the stolen files and return behind the cover (another guard should face other direction).
Once you have stolen files, return to the room where you earlier found a keycard. Interact with a computer terminal shown on the above screen in order to unlock a passage to test facility.
Before you leave this area, I suggest obtaining any disguise (unless you do not want to attack anyone). It is best to obtain factory guard disguise, but if you do not have anything against aggressive gameplay, you can eliminate an interrogated person and obtain scientist disguise right now. Regardless of your choice, head to the newly unlocked passage (screen above), reaching an elevator which will take you to the test facility.