The mayor of Adytum is an old, bitter man. Leading a settlement in the middle of the breeding ground of violence that is the Boneyard, he hired the services of Caleb and the Regulators around 2158, to ensure protection of the settlement. However, the Regulators seized control over the town, by manufacturing plausible stories pitting the Blades, one of the gangs in the Boneyard, in the role of oppressors and barbaric attackers. These include staged attacks on the perimeter and even abductions and killings. The most notable victim of this strategy was Zimmerman's son, tortured, killed, and left on a pole right outside the town gates. Jon swore revenge, giving Caleb carte blanche when it came to dealing with threats to Adytum.
It's possible to prevent Zimmerman's death after presenting the evidence to him, though it's difficult. The idea is to enter combat mode after the script fires and a Regulator attempts to execute Zimmerman, but before the shot is fired. If timed well, the player will only fight the Regulators. Then, the player has to block the entrance to the building with their character, to prevent Regulators from storming the building and killing Zimmerman. They will rush and try to kill the player instead. Note that the game doesn't expect Zimmerman to actually survive. Bugs may occur.