Donald Anderson, codename: Sigint (signals intelligence), first appears chronologically in Metal Gear Solid 3. He isn't present during the Virtuous mission but is later introduced by Major Zero as the replacement for the Boss as part of Naked Snake's radio team. Sigint specializes in technology, having made several pieces of the equipment Naked Snake uses throughout the game; the Active Sonar, the Motion Detector and the AP Sensor. He also has information on different camouflage patterns and face paints, albeit having no experience using them unlike The Boss.
Sigint also provides a lot of humor in the game, whether it's spending his time questioning the sanity of others or telling strange stories of nightmares he has. At the end of the game, Sigint joins ARPA.
In Metal Gear Solid: Portable Ops, Sigint plays a minor role in that he can be contacted for advice, he's also a recruitable character outside of the story.
In between Portable Ops and Metal Gear, Zero creates The Patriots and invites Sigint to be one of its founding members a long with Para-Medic, Big Boss, Ocelot and EVA. During the split between Zero and Big Boss, Sigint takes the side of Zero as he wouldn't have advanced to that point without the opportunities Zero afforded him.
He continues to work for ARPA until it is renamed DARPA.
As the DARPA Chief
Prior to the events of Metal Gear Solid, Sigint, now known more by his real name, Donald Anderson, becomes the head of DARPA. He is one of the main sponsors of Metal Gear REX project, but is imprisoned by Liquid Snake's rogue FOXHOUND unit. One of Solid Snake's objectives upon infiltrating the Shadow Moses Island facility is to rescue Anderson. However, when Snake encounters Anderson in his cell, Anderson dies of a massive heart attack.
Or so Snake thinks at first. It is later revealed that Anderson had actually died prior to Snake's infiltration. Ocelot had accidentally killed him while using torture techniques to force Anderson to reveal his REX launch code. The man that Snake met in the cell wasn't Anderson, but rather Decoy Octopus, a master of disguise and one of Liquid's allies in the uprising.
It isn't until Metal Gear Solid 4: Guns of the Patriots that it is revealed that Sigint and Anderson are one in the same. The truth behind his death is also revealed. Anderson's death wasn't an accident at all. Ocelot murdered him because as one of the Patriots, he would have tried to stop Ocelot's plan to destroy the Patriots, kill Zero and free Big Boss. Anderson could also blow Ocelot's cover to all others present. Because Para-Medic had already been killed by Gray Fox prior to the events of Metal Gear Solid, Ocelot saw the perfect opportunity to rid himself of the last person who could stop his plan.
The last time Donald Anderson is seen chronologically is as a three-day-old corpse kept in the same prison cell as Solid Snake after Snake himself is captured and tortured.
- His codec profile lists him as 24 years old in Metal Gear Solid 3 (1964), making him 65 as the DARPA chief in Metal Gear Solid 1 (2005).
- He stars in "Metal Gear Sigint" in MGS3: Subsistence, it is a parody in which Sigint takes the place of Naked Snake in the game's key moments, with Naked Snake himself always one step behind.