If you want to kill Robert Knox in Hitman 2, one of the best ways is to have his own creations gun him down. Tied to The New Army mission, players will need to assume the role of a military commander so they can infiltrate Knox’s R&D building. In order to kill Knox, you’ll need his photo, but the game doesn’t specifically tell you where to get one.
While you can obtain the photo of Robert Knox at any time, it’s easiest when you’re wearing the military disguise. Once you enter Knox’s building, head up the stairs but don’t follow the signs to the test room. Instead, go up the stairs and head down the hallway to your left. At the very end of the hall is the Conference Room.
Go through the door and at the end of the conference table is a magazine with Robert Knox on the cover. Interact with and Agent 47 will rip a photo of Knox out, which will get added into your inventory. Now continue along with the mission until Knox asks Agent 47 to scan a photo of a target. Pick one off the table, but use Knox’s picture instead of one of the dummy’s.
This will cause the robot to see Knox as the target and instantly kill him. You won’t be viewed as a suspect and his death will be ruled as an accident. If you’re looking for a quick and efficient way to kill him, this is probably the best way.