Season Four Edit
Zombie Runner 5 steals baby Sara Myers-Cohen-Yao moments after her birth. Sam remarks that it looks incredibly similar to Runner 5. This zom becomes enraged and bites Sam several times after he takes Sara and passes her through the window to actual Runner 5.
Later, Runner 5 accompanies Steve The Builder and Kefilwe Lobatse to track down Zombie Runner 5. When they catch it, they realize it's wearing latex makeup to look more like Runner 5. The zom is crushed, but Dr. Lobatse uses a bone saw to cut off its hand.
The Minister of Recovery intended to switch out the real Runner 5 with a plant, but the rocket launcher attack failed. Zombie Runner 5's pre-zombification mission was to access vault Z-92 under Janine's farmhouse and destroy all evidence of The Minister's experiments.