Operating as both an illegal prison camp and para-military training facility by the corporation, Rockfort was administered at the time of it's abandonement by Alfred Ashford, whose father was a researcher for, and whose grandfather a co-founder of Umbrella.
Besides the prison and training facility, the island also features a large subterranean airport holding several C-130 sea-capable cargo planes, at least two harrier jets owned personally by Alfred, a small but lavish palace for hosting of dignitaries, and a private residence for Alfred and his rarely seen sister Alexia on a hill behind the palace, access to and even knowledge of it's existance being tightly guarded by Alfred. Several laboratories and B.O.W. stores are located within the island, including a supply of T-Virus, and at least one T-078 Tyrant variant.
The island population consisted mostly of a mixture of assorted workers, trainees, guards, attendant staff and prisoners. During the outbreak, all bar a handful became zombies. A native population is mentioned in files, but have seemingly been wiped out by the time of the outbreak.
Home to Alfred and seemingly Alexia Ashford. The training facility had been operating for over a decade before the island is attacked by an unknown organisation. During the attack, the T-Virus is unwittingly released, and the remaining island population are infected. Although some manage to escape to the airport and the Antarctic base, which Alfred also administers, the virus had already made it aboard at least one of the planes, quickly infecting the Antarctic base upon landing. During the attack, prisoner Claire Redfield is released by dying Umbrella security chief, Rodrigo Raval, encounters fellow escapee Steve Burnside, island commander Alfred Ashford, the seeming Alexia Ashford, and the leader of the attacking force, ex-Umbrella employee turned rogue agent, Albert Wesker who is looking for Alexia. After sending a distress signal to her brother Chris, and learning that Alexia is really Alfred in drag, who set's the base on auto destruct, Claire and Steve manage to escape the island on a stolen cargo plane, defeating a Tyrant sent by the increasingly insane Alfred, but are locked on autopilot flying to the infected Antarctic base, followed by Alfred in one of his Harrers...
The island is supposedly destroyed when Alfred sets off the self-destruct system for the island, but the device fails to detonate fully. The training facility is left partially standing, although badly damaged, as is the airport and the Harrier facility.
This is how ex-S.T.A.R.S. member and anti-Umbrella activist, Chris Redfield later finds the island, having climbed the cliffs by hand, it's facilities half destroyed, and under the total control of Wesker, although most if not all of his own men appear to have become zombies since Claire's departure. Chris manages to find the still alive Raval in an underground cavern below the training facility, who tells him of his sister's escape, saving him from the Gulp Worm before he finally dies. After encountering Wesker, Chris learns that Alexia is alive, in Antarctica with his sister. Chris manages to access a second Harrier and follow Claire to the Antarctic.
The island is then presumably abandoned as no further record of it is mentioned in later Umbrella documents.