Searching for Proof

Chapter 9 - Corporate Warfare Arie Van Bruggen had no qualms admitting involvement in the attacks against Sarif, and even gave Jensen the name of the woman who'd hired him: Zhao Yun Ru, president of the Tai Yong Medical Corporation. Seems TYM wants to monopolize the augmentation industry, and hired black op mercenaries to destabilize its competitors. But to prove this, Jensen needs to infiltrate the biotechnology giant and locate recorded evidence...

M1 - Searching for Proof is a main mission in Deus Ex: Human Revolution.

Enter TYM's tower by passing through the pangu
Reach the door on the other end.

If you hack the level 2 device on the control panel, you will unlock a button that repositions the catwalk. This lets you bypass security by going to the room in the left and climbing up the ladder. This leads to a vent and a tunnel that drops down, but you will need the Icarus Landing Augmentation to proceed this way.

Find and view van Bruggen's Recording
At the end of the datacore room.

Rescue a TYM employee

 * Level 3 computer hack (there is a pocket secretary with the passcode for the door at the end of the hall on a yellow trolley)
 * Round the back is a level 1 computer hack but requires Implanted Rebreather aug.
 * If you do manage to help him, talk to him and he will tell you to mention Lee to the guard ahead. This lets you get through the guard without having to bribe or persuade him.