They carried communication devices. Not the normal headset with a cool clear coil hanging out of the ear but a short gun stock with a camera system in place of a barrel and receiver. They would point the camera at the movement and pull the trigger. That sent an alarm signal to the human controller to evaluate the threat and monitor the camera feed. You can time an automatically sweeping camera and have a chance of sneaking past, but nothing gets by without our Zombie Security noticing. We had used some Zombies in the past for the intimidation factor and had a rudimentary way of controlling them, but this new thing was pure professional.
Eventually the wall went up and the tunnels and bridges were secured. It was good money and recurring. No one else really wanted it because of the risk factors but we did. I put my number one muscle brother as the head of all of our Zombie Security forces. It was a good place to keep an eye on him.
