Luis is a Spaniard man who is a native of the Spanish village featured in Resident Evil 4. After returning from Madrid, where he pursued a career in the police force, Luis was hired by Osmund Saddler as a researcher for the Las Plagas parasite, experimenting with it to enhance the abilities of the host it infected. After some time, Luis became dissappointed of Saddler's intentions, and he betrayed Saddler by stealing a Plaga sample. Saddler discovered him, and ordered for him to be tied up inside a closet, waiting for his fate. Leon S. Kennedy finds Sera and frees him, making Luis his ally. Luis helps Leon find Ashley Graham, and assists them in escaping Spain, as well as avoiding the Plaga parasite to grow inside Leon.

Inside Ramon Salazar's castle, Luis manages to reunite with Leon and Ashley. Just before giving Leon the plagas sample, however, Saddler impales him through the chest and takes back the sample. In his dying breath, Luis gives Leon some pills to slow down the growth of the parasite, giving him some time to find a way to stop the virus completely (i.e. a plaga-removing machine Luis invented).