Dead Army - Radio Frequency

After starting the tutorial and converting all citizens into zombies, group all your units in a location away from the police group. Then take one (only one) of your fast zombies (green clothes) to the enemy until one or two of them start following you and return to your group. The policemen will follow you and they will be attacked by the mob.

Repeat until all cops are cleared.

After each attack separate the most damaged zombies and send them away so they will not be killed when a police officer approaches.