The Invasion of Chau Sara
- Main article: StarCraft: Precursor
In late 2499, Alpha Squadron was engaged on Chau Sara to eradicate the Sons of Korhal presence there when the zerg attacked. At the time their existence, the zerg was a Confederate secret and were referred to as xenomorphs. Cerberus also deployed to Chau Sara but did not reveal their presence to either Alpha Squadron or Magistrate Collins until it became necessary to contain the zerg.
The Cerberus Commander and Collins quickly developed an adversarial relationship, with the latter resenting the infringement on his authority and distrustful of Cerberus' tactics. Nonetheless Collins enlisted Cerberus' aid to relieve the Flannum Installation. Flannum had been conducting research on the zerg and all communications with the base had since failed. Cerberus and Alpha Squadron fought through the surrounding zerg and gained access to the installation.
Cerberus Firebats then entered the installation to rescue the scientists within. The outfit already knew the installation's codes, something that only Collins should have known, which would allow them to locate the scientists using the base's bio-scanners. Although the zerg were able to evade the scanners Cerberus was successful in rescuing the remaining scientists with the aid of surviving security personnel.
The zerg began attacking Los Andares, capital of Chau Sara. Cerberus joined Alpha Squadron, personally led by Edmund Duke, in defending the city. Once the onslaught had been repelled Collins believed that Alpha Squadron would be better employed digging in around the city and continuing to defend against any further zerg attacks. However, Cerberus' commander favored more offensive action and when Collins objected Cerberus' commander took control of the colony, declaring: "By order of the Colonial Crisis Act under sub-section 1602, I hereby supersede your authority in this matter." Collins and Duke had little recourse but to obey.
The resulting attack on the local zerg hive cluster was a success and the zerg were defeated. Cerberus then imposed an information blackout on the entire operation, stating: "By edict of Confederate High Command, all matters regarding these xenomorphs are under Class 7 Seal. Do not speak of the existence of the xenomorphs or in any way relay the events surrounding their appearance on Chau Sara. Failure to comply with these orders will result in immediate termination. This conversation never took place. We were never here."
Many of Cerberus' members were killed defending the Confederacy during its fall and the outfit vanished. However, not all of its members were accounted for. Tamsen, now a Terran Dominion official, continues to lead the group secretly.