Florencio Roque Fernández was born in 1935 in Monteros, Tucumán Province, Argentina. Suffering from severe mental illnesses, including delusions and hallucinations, he believed himself to be a vampire which a condition possibly linked to schizophrenia. He also exhibited Renfield's syndrome, characterized by a sexual attraction to blood. Abandoned by his family at a young age, Fernández lived in seclusion, residing in a cave near his community and reportedly suffering from photophobia, an extreme sensitivity to light.

Throughout the 1950s, Fernández allegedly murdered approximately 15 women in his hometown of Monteros. He would stalk his victims for days, ensuring they were alone. Taking advantage of warm nights when residents left their windows open, he would enter their homes through these openings. While his victims slept, Fernández would assault them, biting their necks and, in some cases, severing the trachea and carotid artery, leading to their death. This gruesome method earned him the monikers "The Argentine Vampire" and "The Window Vampire."

On February 14, 1960, at the age of 25, Fernández was arrested in a police operation described by the press as "picturesque," as it took place in the cave where he lived. He did not resist arrest until officers brought him into sunlight, exacerbating his photophobia. Declared insane, Fernández was confined to a psychiatric institution, where he died of natural causes in 1968.