Dr. Cameron was an Umbrella Corporation researcher working in Raccoon City.
Unfortunately, before they could get to her, Cameron was infected by the t-Virus. Unwilling to succumb to the same fate as her colleagues, Cameron injected herself with an experimental serum.
The serum had mixed results. Although it halted the spread of the virus, it caused her to mutate into a new form of life, one with tremendous strength. But Cameron discovered the ability to implant her personality and memories into other organisms by injecting them with the tentacles the mutations forced upon the bodies she used, making her practically immortal.
Eventually, after whittling away at the U.B.C.S team, Cameron implanted herself into a monitor - Roger. As Roger and Klaus made their escape from Raccoon, Cameron asserted herself and revealed Roger to be nothing more than a puppet under her control, even shaping his body to alter part of his face to resemble her own. Impaling the unfortunate squad leader with a tentacle, Cameron explained how she had observed the team after she was reduced to a cloud of dust in the Municipal warehouse. Vowing that Umbrella would never get their hands on her research, she used her tentacles to destroy Klaus' head, and presumably escaped in the guise of Roger. What happened to her after that is unknown.
- The canonicity of Biohazard 4D Executer is debatable; although made by Capcom as a side-story to Resident Evil 3: Nemesis, the events have never been referenced in any succeeding canon work.