Claire first met the Chief in his office (after destroying the rubble blocking the corridor) with the recently deceased body of Mayor Michael Warren's daughter on top of his desk. He later disappears from the office after using his secret door to escape to the basement. He left his Diary near the door in which he described his desires to hunt down The Mayor's Daughter and use her body as a stuffed trophy, indicating he was an avid taxidermist. He lies to Claire, claiming that the mayor's daughter died after being attacked by a zombie.
Irons was responsible for the deaths of at least several officers when he went insane and hunted them like game. Additional documents also revealed that the character was previously convicted of sexual assault and had been taking bribes from Umbrella Chemical, Inc., particularly from William Birkin himself. Claire confronted Irons one last time in a hidden room behind his office before he was killed by the mutated Birkin, either indirectly because he rejects the G-virus (which is in the form of a chest-bursting parasite when he dies) or by being torn apart. Irons is always in the same room after he is killed in either scenario ().
Irons had taken personal offence of Umbrella for ruining his town.
Irons was arrested for two rape charges with a university student. He underwent psychiatric evaluation as a result of the charges, but was released due to circumstantial evidence as well as his phenomenal academic standing. His criminal history is found out through a letter sent to Chris Redfield from the FBI that can be picked up by Claire Redfield in the S.T.A.R.S. office.
According to his financial records, Irons had been accepting Umbrella bribes for five years before the Raccoon City outbreak.
Brian Irons made a small appearances in the Mini-Game, The Mercenaries - Operation: Mad Jackal in Resident Evil 3. You meet him at the end of the mini game when you arrange to get inside the Store, where Resident Evil 3 starts. However you can only see his silhouette.