From Halopedia, the Halo wiki
Herzog was an Office of Naval Intelligence Colonel ostensibly in ONI Section Three, although he was secretly working for Section Zero. He led a variety of investigations for several years along with his friend Avi. When Avi retired, he continued to remain active despite his friend's encouragement that he join him in retirement. Although Herzog had been married, it ultimately ended in divorce.
Herzog's interest in the ONI Prowler UNSC Apocalypso began with him recruiting MacKaskill, the ship's mechanic, whom he instructed to report to him should anything notable occur. It's possible that Herzog learned through him that the Apocalypso had intercepted Covenant transmissions detailing upcoming attacks on the UNSC colony worlds of Troy and Harmony; however when the ship picked up the mysterious Deep-Space Artifact, MacKaskill's attempt to contact him was thwarted, by the ship's AI, Melissa, who knew that if the transmission was sent MacKaskill could be tried for treason and felt protective of her crew member.
When the artifact's activation caused a bizarre Slipspace anomaly that crashed the ship in Lunar orbit and disrupted all communications within the Solar System, Herzog's interests extended to the ambitious Major Standish. Standish believed the artifact to be a prototype of a new Covenant weapon and sought to uncover its secrets before anyone else. To do this, he had everyone who served aboard the Apocalypso suffer a fatal "accident", and moved the artifact into his own lab for study.
Herzog, however, managed to speak to the Apocalypso's CO, Captain Greene, before her vehicle drove her into the path of a bus, and he learned of the artifact. On Avi's advice, he recruited a young analyst named Rani Sobeck to help him keep an eye on Chawla Base, where the artifact was housed, as well as some investigative work into the matters of Troy and Harmony. Proud of her work, he accidentally gave away too much information while trading banter with Standish, leading to the latter's attempt to assassinate her. Herzog's sniper took out Standish's assassin with a Hard Sound Rifle before he could get to Rani, and Herzog was able to use the incident to get Standish in trouble with an Admiral. In retaliation, Standish had Herzog's car drive him at full speed over a cliff, killing him.
Despite Herzog's death, his persona was taken over by a fragment of Melissa, who was split apart with the artifact's activation, known as the Operator. The Operator, desperately needed to communicate how to deactivate the artifact to another of Melissa's fragments, known as Durga, but was afraid that Durga wouldn't trust her. She manufactured a scene between Herzog and MacKaskill detailing the artifact's activation sequence, disguising it as surveillance Durga took while spying on Herzog. It worked so well that she was later startled to learn that Herzog had indeed died in the crash.
On September 12, 2552 two individuals known as Mike44236 and Echo23023 shared a conversation through sub-chatter. Among the things they mentioned was an agent known as Sierra10852, implied to be Standish, who was executed for killing Herzog.
Personality and traits
Herzog often liked to use a fake voice called "The Cranky Old Man" to complain about things.
List of appearances