It is stated in an audio log that at some time before the events of Doom 3, Betruger inexplicably entered a teleporter, transporting him to Hell. When Betruger returned, he still looked the same, but he behaved differently. This suggests that Betruger may have been possessed or corrupted by a demonic force, though it is never clearly stated exactly what happened to him. What is clear is that he had made a pact with the demons of Hell in which he agreed to provide a portal that the demons could use to invade Mars City, in return for great supernatural power, including a degree of omnipresence and the ability to command armies of demons. Shortly before the invasion, Dr. Betruger acquired the Soul Cube. Knowing that it was the only thing that could stop his plans, he hid it in Hell where no one could find it and use it against him.
Betruger is first seen at the beginning of the game, inside of the Mars Facility Control Tower. He observes a shuttle arrive, carrying Counselor Elliot Swann, Jack Campbell, and a replacement Marine. Later, the Marine eavesdrops on an argument between Betruger and Swann, the latter of whom has been sent by the UAC Board to investigate the disturbing activity surrounding Betruger's experiments. Betruger warns Swann to stay out of his way and cryptically adds that "amazing things will happen here soon." A short while after the demonic invasion, the Marine overhears yet another argument between Betruger and Swann. Betruger appears to be unperturbed by the disaster unfolding around him, and smugly tells Swann that he'll "handle" the situation.
Later in the game, Betruger contacts the Marine directly and makes it clear that he is in league with the demons and is plotting to lure the Earth Fleet to Mars. Once they have seized control of the Fleet's ships, they will launch an invasion of Earth itself. A cutscene later reveals that he has gained supernatural powers which enable him to transform other marines into Zombie Commandos. He makes two separate attempts to kill the Marine, first by flooding the area with toxic gasses, and later by opening a portal that pulls the Marine into Hell itself (which was where the Marine was planning on going anyway in order to retrieve the Soul Cube). He also apparently tries to kill or harass the Marine on other occasions, including by destroying the Monorail Skybridge, and is most likely responsible for making the Monorail speed out of control and crash while the Marine is taking it to Delta Labs.
Throughout the game, Betruger continues to taunt the Marine and sets his demonic minions upon the player. He typically threatens the Marine with death and the promise that his soul will burn in Hell forever. Ultimately, however, Betruger's plans are foiled when the Marine recovers the Soul Cube, returns to Mars, and uses the Cube to destroy the Cyberdemon, and seal the Hell Hole that has been opened below the planet's surface. Five days later, a team of marines and sentry bots arrive at the facility. They rescue the Marine, but are unable to find Betruger. The last scene shows Betruger in Hell, where he has become part of a horrific skeletal dragon-like demon later revealed to be the Maledict.
It should be noted that while in Hell, the Marine is taunted by an unseen presence - one that sounds different than Betruger's normal voice. It is unknown as to whether or not this is still Betruger or an entirely different entity. It most likely is, as the sound files in the paks have the taunts suffixed with bet_, most likely short for Betruger.
Resurrection of Evil
At the end of Doom 3, Betruger is shown in Hell having been transformed into the Maledict, a giant skeletal dragon-like demon. The Maledict is featured more prominently in the Doom 3 expansion pack Resurrection of Evil, and is the final enemy of that expansion.
When a marine, a combat engineer, finds the Artifact, he triggers another Martian invasion by the forces of Hell. Betruger sends the Hell Hunters to retrieve the Artifact from the marine. When the hunters are defeated and their essence is absorbed by the Artifact, the marine later fights his way to Hell to destroy the Artifact. In Hell, the Maledict demands that he give him The Artifact. When the marine refused, the Maledict attacked and caused him to pass out. When he awoke, the Maledict demanded the Artifact again, but the marine instead shoved the Artifact into Betruger's mouth, causing an explosion that killed the Betruger/Maledict demon.
- Betruger's name comes from the German word "Betrüger" which means "deceiver", "cheater" or "swindler." It also sounds a lot like the word "betrayer," though the actual German word for "betrayer" or "traitor" is "Verräter."
- Dr. Reinhard from Evil Dead: Regeneration has several similarities to Betruger. In addition to looking similar (with a solid white eye), both were said to have been good before their pacts with evil. They also have German names.
- If on the first level, if you use cheat codes to enter the room where Betruger is, he will be identified as "Joe" - the name for all NPCs the player is not supposed to be able to interact with. He has no lines and will not speak with you.
- By using the method, he can be killed but this will not affect the storyline in any manner,
- Curiously, upon closer inspection, it is revealed that he was looking at a screen of the soul cube.
- According to the Making of Doom III book, many of Betruger's lines and actions were to be performed by General Hayden, the commander of the military on Mars. Hayden was meant to be the assumed villain, and only later on in the game would it be revealed that Betruger was the true mastermind behind the invasion. Later, the developers decided to remove Hayden's character entirely, and establish Betruger as the villain early on in the game.
- Betruger and Mr. White (Area 51 game) are equivalent (they're bald and almost have the same outfit).
- In Resurrection of Evil, Betruger's blind eye appears to have changed from his right eye to his left eye.
- Betruger is the first human antagonist in the Doom series.
- In Betruger's office a picture of the so called Face on Mars can be seen on a wall, which is believed by some to be the remains of an ancient Martian civilization. This fits with the setting of ancient ruins found on Mars in Doom 3, though is probably just a joke of the developers, and not a part of the background story.
- His face and voice are a homage to the actor Sir Anthony Hopkins, who played Dr. Hannibal Lecter in The Silence of the Lambs and Hannibal.