I am stuck at the retna scan. I think you are suppose to choke someone and bring them to the door. But everytime i do that i knock the person out. So how do you choke them. And how do you open that door.

Just hold the choke button down until the guy starts to shake, then release and hold the button quickly, then repeat when necessary.

Basically wait til a guy gets close to the scanner and choke him. Drag him over to the scanner and shove his face in it. You just have to be pretty close before the door opens. If you still are having problems with them passing out, try the release method mentioned above.

thanks it worked