Eladio Buente (played by Raymond Cruz) was a Mexican immigrant who, after being exposed to a toxic substance, became an unknowing carrier for a contagious fungal pathogen due to an inherent immunity that prevented the normally fatal spread. During the subsequent search for him, he inadvertantly infected several people he came into contact with and gradually underwent physical mutations himself, becoming associated with a legendary creature named El Chupacabra.
1997 mutation and manhunt[]
Eladio was a manual laborer who lived in a shantytown populated solely by Mexican migrant workers in San Joaquin Valley, near Fresno California, with his older brother Soledad. Both Eladio and Soledad were in a love triangle with a local woman named Maria Dorantes, who was seemingly being won over by the younger sibling. During one such flirt between the pair, the town's goats escaped their enclosure into the desert and shortly after the lovers ran to fetch them from the hills, a massive thunderstorm erupted, bearing a strangely yellow tinge. When the villagers went out to search for the two and livestock, they discover Maria and one of the goats dead in a puddle of rainwater, both their facial orifices heavily disfigured by rot. The superstitious townfolk come to believe that a creature from Mexican urban legend, the goat-killing monster known as El Cupacabra, must have been the culprit, but bizarre condition of Maria's body leads to the FBI dispatching Special Agents Mulder and Scully, who seek assistance by consulting INS agent Conrad Lozano to aid in the search for the missing Eladio, the only potential witness and suspect in Maria's death.
It is soon discovered that Eladio, being an undocumented immigrant, had already been found and interned near Fresno, though registered under the alias "Erik Estrada", before he was identified by fellow detainees at the INS center, who derogatorily and fearfully name him "El Chupacabra". He is questioned by Mulder, with Lozano acting as a translator, in his involvement in Maria Dorantes' death, wherein he denies any criminal action, instead providing his own recollection of the events, saying that when he and Maria had caught up to the goats, Eladio lost consciousness after being blinded by a flash of light. When he awoke, Maria, her face partially eaten away, laid beside him, dying in Eladio's arms thereafter. Eladio insisting that he had only fled because he knew that the blame would be cast onto him, fearing retaliation by his brother in particular. Though Mulder is intrigued, Lozano brushes Eladio's claims off as a poorly conceived cover story, and has Eladio deported, loading him into a transport bus to Mexico to face trial there.
Shortly after, Scully discovers that Maria's corpse had become completely enveloped in growths since she was brought into the coronor's office and further examination proves that she had died of "natural causes", or at least not by homicide, having instead succumb to an intense infection brought on by aspergillis, a normally benign fungus variant. With Eladio's guilt cleared, the pair drives to the holding center to share this turn of events with the immigration office, but on the way, they find that the INS bus had crashed, and now empty of passengers. The agents discover that the driver had died to the same fungal infection as Maria. Analysis by a mycologist reveals that they were dealing with a different, but similarly harmless fungus, but that in the cases of both Maria and the driver, traces of an unknown enzyme were found, which appeared to act as an extremely potent growth accelerant and sent both victims into fatal systemic shock. Considering Eladio is the unifying factor in both outbreaks, a search for Eladio is organized. Scully concludes that Eladio was an asymptomatic carrier of a potent fungal enzyme after coming into contact with it in the rain water, which Mulder opines must have been of extraterrestrial origin and that the thunderstorm was a result of a meteorite crash, which evaporated in the atmosphere and contaminated the rain clouds with the enzyme it contained.
Meanwhile, Eladio is trying to get an acquaintance, known as El Barbera, to take him back to Mexico in order to escape Soledad's wrath. Without any money to pay him, Eladio looks for freelance work at the roadside, eventually being hired by Rick Culver to do some construction after his mere presence scares away the remaining laborers. He flees his workplace when Soledad tracks him down with murderous intent and manages to convince his cousin Gabrielle, an au-pair for a wealthy family, to hand over her month's salary, but has to lay low until she gets paid later that night. By this point, his infection has made its way to his sweat glands, making Eladio an even more virulent vector of the enzyme, unknowingly having caused Culver's death by fungus just minutes after their arrival inside the site's portable toilet. During his flight, he is spotted by Mulder and Lozano patrolling the area, but is able to shake them off after jumping into a truck transporting goats. By the time they catch up on the highway, all the goats are dead and covered in fungus, with Eladio again nowhere to be found. They question Gabrielle on her knowledge and instruct her to keep them informed to ensure the safety of both Eladio and Soledad.
Having gone without food for several days, Eladio, visibly unwell with numerous open sores on his swollen forehead, enters a supermarket and attempts to swipe some cashews at a self-service display, unintentionally contaminating the whole stock, but is chased away by a clerk. Soledad, having been tipped off by the local community, shows up shortly after, where he is arrested by the agents, who find that the self-service aisle, along with the clerk, have been completely enveloped by fungus. Eladio attempts to meet with Gabrielle at her house, but she is horrified to find that Eladio has become mutated, with his head having swelled up immensely, his eyes turned pitch black and his skin turned a bluish-grey color, declaring that he had become the feared Chupacabra of legend and runs off to return to the migrant camp, where he is faced with Lozano and Soledad, as the former had decided that keeping Eladio alive was too great of risk to take. Soledad, experiencing second thoughts, relents after being given a gun, leading to a struggle in which Lozano is shot and both brothers escape just as a hazmat unit arrives to quarantine the camp.
Lozano's gun is found near the car of El Barbera who had apparently been paid by the brothers to take them back, but was inadvertantly infected along with Soledad, who also proved immune to the enzyme and has begun to mutate as well. The FBI is unable to located the Buente brothers, who are last seen hitchhiking along a highway in rural Mexico.