Marcus Caseon



Union Aerospace Corporation



First appearance

Mars City (later heard in audio log)

"I'm getting off this rock, and you should too."
― Marcus Caseon to the Marine [src]

Marcus T. Caseon, or just "Mark", (Identification Number: 1394-39) was a doctor assigned to Mars City. One night, a patient came to him complaining of insomnia. Marcus then went to get the right medicine for the patient. When he came back twenty minutes later, the patient had become incredibly hostile and attacked Marcus, though Marcus survived the attack. Shortly afterward, he requested to leave Mars. His request was granted. He was scheduled to leave on the same ship that delivered Counselor Swann, Jack Campbell, and Marine Transfer to Mars. Before leaving, he encountered Doomguy. Marcus, still disturbed from his patient's attack, warned Doomguy not to trust anyone on the base, and that strange activities were taking place on Mars.

He was one of the ones scheduled to fly off of Mars, and transfer back to Earth via Burns Flat, OK on board the Darkstar. As the Darkstar returns to pick up survivors at the end of the Lost Mission its possible he may have left when it took off in the first place (as he was close to the shuttle).

PDA Contents

Audio Logs

High Incidence of Psychological Reports

Audio log for Doctor Caseon, currently stationed at Mars City.

I have just left the weakly status meeting here in Medical. The most prominent topic was the vast number of psychological issues we are seeing as of late. The number of reports indicates that 10% of the overall base personnel have shown symptoms. As many people will not come in for this type of thing, the number of affected personnel could truly be in the 30-40% range. It has even manifested itself here in Medical. We, uh, have several nurses and a couple of good doctors out for related reasons. I'm going to formally request two additional psychiatrists on the next shuttle from Earth. The two we have are being overworked and the content of their sessions with patients is starting to affect them as well.

Doctor Caseon out.

Patient Attack

Doctor Mark Caseon.

At 15:47, patient Jonathon Wills was admitted after complaining of insomnia and nausea. According to the nurse, Mr Wills was calm and exhibited no signs of disorder when he was brought to Exam Room 5. However, by the time I reached him at ten after four, his personality had changed dramatically. When I entered the room, Mr Wills lunged at me with a scalpel he apparently stole from a supply drawer. With the assistance of an orderly, we managed to subdue and sedate him without injury. Mr Wills was heavily medicated and could not be diagnosed, but in the 20 minutes he was left unattended he managed to carve three symbols in his arm and cut his own tongue into... two halves. I... I can only guess at the cause of his problems. I hope that additional psychiatrists arrive soon. In the meantime, in response to this assault, all medical supplies and armaments will be locked in a secure hospital cabinet with the code 347.

Doctor Caseon out.


RE: Patient Attack (11-09-2145)

Thank you for sending me the audio report. I wish the news was better.

I will coordinate with our colleagues here on Earth to find additional staff and resources to assist. Given the situation there, it isn't going to be easy. You may be on your own for a while.

My advice to you, continue to document everything you can, attempt to find the root of the problem, and for goodness sakes, stash weapons and medical supplies for yourself in case things get worse. I'm glad to hear you've already taken some precautions by locking some supplies in that cabinet. I hope it is enough. I appreciate you including the code in your report and will keep it secure.

Leaving? (11-15-2145)


I hear that you're leaving Mars. I'm happy that you'll be able to spend more time with your family, but I am very worried about the deteriorating situation here. We're short staffed already. Your departure will be a big loss.

Speaking of which, I've noticed that Zach in Operations has been behaving more and more erratically. Since talking with you I'm not sure if I'm being overly sensitive, or if he has caught the bug going around. I swear he tried to bite me today.

In your absence is there anything I should do?



  • Marcus Caseon is not encountered in the Xbox port of Doom 3, as the area where he is sitting is replaced by a pre-rendered FMV. Nonetheless, his PDA can still be found on the revisit of Mars City.
  • Despite the fact that Marcus was at the Landing Bay and was waiting to leave onboard Dropship 4409, the dropship wouldn't leave Mars until 18:55, more than 12 hours and 30 minutes after it arrived (as seen on the Arrivals/Departure screen in the Departure Lounge). Also, Dropship 4409 started refuelling shortly after landing. However Lost Mission confirms that the ship must have taken off during the initial invasion to escape, and it returns to pick up the Bravo Team Member and a few other survivors.

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