Outbreaks
Ten years after Marcus' assassination, however, a disaster struck the Umbrella Corporation. Despite having seemingly been killed, Marcus came back to life through the T-virus. Marcus exacted his revenge on Spencer and Umbrella by releasing the T-virus into the Arklay facilities, turning the personnel into zombies and leaving the facilities in complete chaos, allowing dangerous research specimens to escape into the surrounding area. Included in his anti-Umbrella activities, he also released the virus in the Management Facility, which Umbrella was refurbishing for possible re-use. A train transporting Umbrella personnel across the Raccoon Forest was a third target.
Birkin and Wesker used this as a diversion for their own plans to leave Umbrella, taking their research with them. Wesker, having formed Raccoon Police Department's (RPD) STARS two years earlier, would develop a plan to lure the unit to the Arklay Research Facility to obtain battle data from the conflict that would follow with the STARS and various Bio-Organic Weapons (BOWs). Of the two STARS teams, the first to be deployed was Bravo team, and it was Bravo team's Rebecca Chambers' and Billy Coen's intervention that eventually stopped Marcus's plans for revenge within the Arklay Training Facility, resulting in the facility's destruction.
Bravo team was followed by Alpha team. Both suffered heavy losses while battling the BOWs. In the Arklay Research Facility, one of Umbrella's most potent BOWs, the Tyrant, was released, resulting in unforeseen side-effects for Wesker. In the end, both the laboratory and the rampaging Tyrant were destroyed by STARS.
Wesker was forced to go into hiding for a number of months, using his operative Ada Wong to carry out his objectives, including the recovery of Birkin's ultimate creation, the G-virus. Several months after the Arklay incident, Birkin finally perfected the G-virus. Birkin planned to use the virus to force the Umbrella Corporation into allowing him onto their executive board.
Umbrella deployed its Special Forces Unit in a bid to steal a G-virus sample from Birkin. Although Birkin was mortally wounded in the ensuing conflict, and the G-virus was successfully recovered by Umbrella, he was able to inject the G-virus into his own body and kill most of the team before it could make its escape.
This event was directly responsible for unleashing the T-virus on Raccoon City. While the Arklay incident had been relatively isolated and concealed from the public, and Umbrella's control over key government and law enforcement personnel had ensured that any record of what had occurred could be safely swept into obscurity, they were now faced with an entire city infected with the T-virus and a trail leading directly back to the Umbrella Corporation.