After you go to Diaz to start the mission, check the window, get upstairs, then start chasing the thief. If you are good enough at sprinting and weaving in and out of tight spots, you will pass him up on the roof and jump off the edge of the building first. Then, get in the BF Injection and wait. The theif will jump down, get in, and drive you there. You will appear to be invisible at the end of the mission. Get out of the car, and you will have completed the mission by doing very little.