(Capcom's primary storyline)
On May 12, 1998, weeks prior to the Special Tactics And Rescue Service's investigation of the Arklay Mountains and its associated research outpost, the keeper was infected by the t-Virus after Queen Leech intentionally released the experimental mutagen as revenge on behalf of Dr. James Marcus against Umbrella, although he assumed the leak was accidental due to the research staff being sleep-deprived.
He wrote down his progress through infection of the virus as it destroyed his sanity day by day from May 9, 1998 until June 4, 1998. Because of this, he would neglect to feed the Cerberus, which led some of them to escape from their cells, culminating in the keeper hiding the flight of his superiors for fear of retaliation. When his mental stability finally breaked on May 19, he killed a fellow employee; Scott, for having an "ugly face", and then, based on his response being "tasty", consumed the corpse.
During the exploration of the mansion by the S.T.A.R.S. on July 24, an Alpha team member found the keeper's diary in his bedroom, and was attacked by a zombie hiding in the nearby closet, which may very well have been the keeper himself.
With that diary, the S.T.A.R.S. member obtained a crucial evidence of what actually transpired in the mansion.
- Despite the character not being directly named, in the original version of Resident Evil, the name 'Peter' can clearly be seen on the front of the file. The surname also begins with an 'S', and quite closely resembles 'Smith'.
- Some time between the release of the virus in the mansion in May and its destruction in July 1998, the Keeper's diary was duplicated and sent to Oswell E. Spencer. Jill Valentine and Chris Redfield would find this copy over a bedroom desk in the Spencer household in 2006.