Sigint helped Naked Snake during Operation: Snake Eater and later on became a founding member of the Patriots. His real name is Donald Anderson who later becomes the DARPA chief who Solid Snake encounters on Shadow Moses Island in Metal Gear Solid. During MGS3 Sigint is there to provide Big Boss with intel and tips, regarding weapons and gadgets, including the camouflage system. He also give hints and tips on how to beat bosses.
At this stage in the Metal Gear time line Sigint is in line with ARPAnet (later to become DARPA). ARPAnet offer help by sending a unit of Green Berets to help Snake. However soon after deployment, ARPAnet loses contact with the berets, one of them being Roy Campbell (a vital main character in later titles). Sigint also helps by suggesting to Snake that he should start to recruit the low morale troops of the Red Army.
Sigint is killed by Ocelot during a torture session, but Ocelot covers it as an "accident", though he was killed by reason. Decoy Octopus then transfers Sigint's blood to his own body, and changing almost every detail about himself to look like him. Solid Snake finds Sigints body in a jail cell, with all blood drained, but unknowing of the fact that it is the real DARPA chief.
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