At some point prior to 2161, Zimmerman became the mayor of the town of Adytum. Through trickery and deceit, the Regulators convinced him that the Blades are responsible for the death of his son, Jason, who had lived outside Adytum and was secretly in a relationship with the leader of the Blades, Razor. Due to this, Jon held an undying hatred for the Blades and would pay well anyone who killed their leader. Truthfully, his son was brutally murdered and decapitated by two members of the Regulators, who wanted an excuse to get rid of the Blades for good. The Regulators's leader, Caleb also wanted Jason dead due to his relationship with Razor. After Jason was decapitated, his disembodied head was placed on a stake for Jon to see, triggering the conflict between the Zimmerman and the Blades. Much later on, Jon can be executed by his own Regulator bodyguard depending on the actions of the Vault Dweller. After hearing Razor's holotape recording of the Regulators planning to murder Jason, he is killed with a shotgun for discovering the conspiracy to destroy the Blades.
Kill Razor: When first spoken to, Zimmerman will explain the recent occurrence of his son's death. Put simply, he offers the player character 2,000 caps to execute Razor, having been tricked into thinking the Blades are at fault.
Free Adytum from the Regulators: Zimmerman can be talked to about the Regulators around Adytum. If the truth about his son's death is revealed, he is quickly murdered by his own bodyguard, which triggers a battle between the Vault Dweller and the Regulators.
Although extremely difficult, it is possible to prevent Zimmerman's death at the hands of the Regulators:
Prior to initiating the conversation with Zimmerman to expose the Regulators, position the Vault Dweller between Zimmerman and his Regulator Bodyguard As soon as the conversation ends, enter combat mode. The timing is critical; wait too long and the Regulator will get off the first shot, but acting too quickly can set all of Adytum as being hostile. Tactically, the idea is to use the Vault Dweller as a combination mobile shield and firebase. Once the Regulators in the room have been eliminated, the Vault Dweller should, for best results, station themselves in the exit door, plugging the way out and trapping Zimmerman inside. As the Regulators hurry to the building, they can be picked off as they round the corners.
If the battle manages to get to the street, keeping Zimmerman alive becomes much more difficult, but still possible. Keeping an eye on all lines of fire between Zimmerman and the Regulators becomes the primary issue. Station the Vault Dweller between a ranged-armed Regulator and Zimmerman, and try to gun down first other ranged-armed Regulators, then any melee Regulators trying to close on Zimmerman. With a little luck — and a lot of ammunition — the battle is winnable. However, since the game doesn't really expect Zimmerman to survive, his reactions following the battle are a little quirky.
If Zimmerman is alive after the battle, using the method above, it is possible that he will become hostile and attack the PC. The rest of the citizens are now hostile towards Zimmerman. Killing him will not make the rest of the citizens hostile.