|Political and military information|
During the Human-Covenant War, around 2546, 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. The team, comprised of pilot Lian Devereaux, Dr. Evan Phillips, Spartan Naomi-010 and AI Black-Box, were tasked with sowing discord amongst the dis-organized Sangheili. On their way to the initial briefing in HIGHCOM Facility Bravo-6 in Sydney, Mal and Vaz stopped by in the ruins of the Parthenon bar 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 the prowler UNSC Port Stanley, participating in several missions. They provided arms to Avu Med 'Telcam and the Servants of the Abiding Truth, a faction opposed to the allies of Thel 'Vadam.  He and Vaz later extracted ONI agent Mike Spenser from the planet Reynes, where they 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 an onboard Huragok, Requires Adjustment.
In February 2553, 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.
In March 2553, Evan Phillips, accompanied with a fragment of BB, left Kilo-Five to study Sangheili culture on Sanghelios. Mal had warned him not to get killed on his journey. Shortly after, Mal and Vaz were assigned to meet with Spencer on Venezia. Once in Spenser's hideout in the city of New Tyne, Spencer showed them pictures of all the insurrectionist leaders based on the planet. They looked through the pictures and found one of them to be Naomi’s father, Staffan Sentzke. However, their investigation was put on hold after an explosion in Ontom, Sanghelios severed Kilo-Five's communication with BB's fragment and Phillips. They were retrieved by Port Stanley and sent in to recover him.
Mission on Sanghelios
Arriving at Sanghelios during 'Telcam's assault on Vadam, Kilo-Five searched for Phillips in the Temple of the Abiding Truth. They were initially refused entry into the temple by Olar because they were nonbelievers. As BB negotiated with him, a nearby Sangheili crowd became aggravated by their presence. Olar relented and allowed Kilo-Five inside the temple. After they realized that Phillips was no longer inside, they evacuated as the Sangheili mob stormed the area. 
BB eventually located Phillips through an intercepted communication and they quickly traveled to Nes'alun Keep in Acroli to evacuate him. They extracted Phillips in the midst of a skirmish at the keep. During their evacuation, their pelican Tart-Cart was damaged by a Banshee, forcing Devereaux to put her down for repairs. They were followed by a Phantom piloted by Forze 'Mdama, who had been sent by 'Telcam to recover Phillips for them. After being instructed to help them with repairs, Forze handed over some pipes and wire and left. Devereaux was then able to get Tart-Cart off the ground.
On their flight back to Port Stanley, a fire erupted and they had to re-route to the UNSC Infinity. There, they witnessed Infinity in action as it helped the Arbiter by destroying many of the Abiding Truth's vessels. Parangosky then ordered them to extract their informant 'Telcam from the ground. As Kilo-Five abducted 'Telcam from the battle, Port Stanley posed as a Kig-Yar pirate ship and destroyed a few of 'Vadam's ships in order to maintain the stalemate between the two factions. Kilo-Five dropped 'Telcam off on New Llanelli and were later retrieved by 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: Mortal Dictata, page 185
- ^ Halo: Glasslands, page 64
- ^ Halo: The Thursday War, page 429
- ^ Halo: Glasslands, page 35
- ^ Halo: Glasslands, page 67
- ^ Halo: Glasslands, page 237
- ^ Halo: Glasslands, page 456
- ^ Halo: The Thursday War, page 179
- ^ Twitter: Mal started in my mind as...