(Capcom's primary storyline)
During the outbreak of the t-Virus within the mountain town of Raccoon City, Roger was sent in to capture the scientist Dr. Cameron or, failing that, retrieve her research data. He was exposed to her cells and possessed by her consciousness. His body was used by Cameron to escape the city. What happened to the two of them after that is unknown.
- Exactly how Roger got infected by Dr. Cameron's cells is unknown, but one possibility is this:
During the investigation of Dr. Cameron's lab, Klaus got angry at Roger and shoved him. Roger landed on the body of the zombie dog (the killer of Dr. Cameron) that Klaus shot previously. Roger got smeared by the dog's blood, thus infecting him and transferring the doctor's consciousness into him.