(Covers information from the D.C. comics)
S.T.A.R.S. was a special police force operating in the United States. It was secretly being run by Umbrella, who had agents planted in the organization to make sure they weren't being investigated.
S.T.A.R.S. was already several years old at the time of the Mansion Incident, and had a number of branches around the United States, varying in size. Until the Summer of 1998, the Raccoon S.T.A.R.S. branch consisted solely of Joseph Frost, but this changed due to the murders in the Arklay Mountains. With Umbrella being responsible for the murders due to their release of the T-Virus, they assigned their mole, Albert Wesker, to lead a team. Transferred to Raccoon City, he requested the re-assigning of a number of other S.T.A.R.S. members from other branches into the unit. When Umbrella's role was uncovered and Wesker killed, the surviving four members (Chris Redfield; Jill Valentine; Barry Burton and Rebecca Chambers) feared being hunted down by S.T.A.R.S. headquarters due to Barry's knowledge of the G-Virus project, and made preparations to leave once their work was completed. Barry and Rebecca were re-assigned to other units and left the city, believed by Chris and Jill to be part of Umbrella's plans. Chris and Jill decided to leave Raccoon City, with the rookie police officer, Leon Kennedy to be handed the case documents once arriving. Meanwhile, S.T.A.R.S. sent Barry to a psychiatrist in his new town, coincidentally being built above an Umbrella facility and suffering from a T-Virus leak. During the Raccoon City outbreak, Leon Kennedy returned after leaving Claire Redfield, bringing in a "mop-up" team. Patrick Brady, a Raccoon Zoo worker, was infected with the G-Virus but was saved by a S.T.A.R.S. Medical Team. He was later selected by Chris and Jill to be part of their "Charlie Team", an unauthorised S.T.A.R.S. team operating as a vigilante anti-Umbrella force.