In the beginning of the E3 2000 demo, McLees, Wang, Sergeant Stacker, Laine, Geoff, and Segur were to infiltrate a Covenant-held bunker. When the squad entered the bunker, they were ambushed by Elites and retreated topside. McLees and Geoff were the only ones alive after the ambush. McLees covered Geoff long enough for Geoff to make an escape. The Elites incapacitated McLees with shots to his torso and legs. McLees was killed when he detonated his own fragmentation grenade, killing an entire Elite squad and destroying several Covenant vehicles.
- A Marine resembling McLees can be seen in the final game. In the "Jenkins Helmet Record," when Keyes approaches the dead Elite, he can briefly be seen in the background.
- McLees was named after Robert McLees, a weapons designer and animator from Bungie.