|Political and military information|
During the Human-Covenant War, Geffen served in the same unit as fellow ODSTs Vasily Beloi and Emanuel Barakat and a solid camaraderie developed between them. During a battle on Imber near the end of the war, Geffen, Beloi and Barakat hijacked a Spirit to exfiltrate from the planet, later leaving the dropship on Criterion.
In January 2553, Mal Geffen and Vaz Beloi were hand-picked by the Office of Naval Intelligence Commander-in-Chief, Admiral Margaret Parangosky, to serve under Captain Serin Osman as part of a black operations team designated Kilo-Five. On their way to the initial briefing in HIGHCOM Facility Bravo-6 in Sydney, they stopped by in the ruins of bar Parthenon to raise a drink in honor of their friend Emanuel Barakat, who had been killed in action during the final stages of the war.
As part of Kilo-Five, Geffen served aboard UNSC Port Stanley, participating in several missions. The team was tasked with sowing discord amongst the now-disorganized Sangheili by a number of means, including providing arms to the Servants of the Abiding Truth, a faction opposed to the allies of Thel 'Vadam.  These included the extraction of the ONI agent Mike Spenser from Reynes, where Geffen and Beloi were involved in a brief firefight with several Kig-Yar who were attempting to claim the team's dropship for themselves. At one point, Kilo-Five seized the Covenant cargo ship Piety and successfully captured a Huragok, Requires Adjustment. Geffen and Beloi were also present during several arms transactions between Kilo-Five and the Servants of the Abiding Truth.
After ONI had established communications with the human survivors inside Trevelyan, Admiral Parangosky ordered Kilo-Five to arrest Dr. Catherine Halsey. Geffen accompanied the party that entered the shield world via dropship, detained Halsey and brought her, along with the other survivors, aboard Port Stanley.
- Geffen's medical zap badge reads "A+/NO V-CIN" indicating his blood type is A+. The meaning of "NO V-CIN" is not clear, however NO may mean "nitric oxide" suggesting he may have at one time suffered from pulmonary embolism or angina.
- While writing Halo: Glasslands, Karen Traviss originally envisioned Mal as being Australian, but later changed his nationality to British.
 List of appearances
- ^ Twitter: BTW, re Halo Glasslands
- ^ Halo: Glasslands, page 181
- ^ Halo: Glasslands, page 83
- ^ Halo Waypoint- The Halo Bulletin: 10/12/11, Exclusive Book Excerpt - Glasslands
- ^ Halo: Glasslands, page 387
- ^ Halo Waypoint — 343 Sparkast #5
- ^ Halo: Glasslands, page 64
- ^ Halo: The Thursday War, page 429
- ^ Halo: Glasslands, page 35
- ^ Halo: Glasslands, page 67
- ^ Twitter: Mal started in my mind as...