Farfarello were developed at some point prior to the Queen Zenobia Incident, created through infecting Hunters with t-Abyss Virus. In 2005, BSAA chief Clive R. O'Brian provided a pack of Farfarello for Il Veltro, a small paramilitary named after the 2004 Italian movement. The group lost control of their pack at their base in Valkoinen Mökki Airport, resulting in a plane crash and the loss of all ground forces. This also resulted in the crashing of a cargo plane that Chris Redfield and Jessica Sherawat witnessed, due to one of the Farfarello being sucked into the engine while it was attacking it. Later on, the Farfarello were encountered by BSAA officers dispatched to the area.
A file found near the crash site implied that these Hunters were intended to be a prototype B.O.W. that could be controlled while being administered prescribed sedatives. It also stated that these B.O.W.s were unpredictable and impossible to control without hourly sedation. During the transporting of the Farfarello's, their sedatives had worn off, explaining their attack on Il Veltro's base and aircraft.
Following Quint Cetcham's data mine of an II Veltro computer terminal and discovered incriminating evidence against Morgan Lansdale of the FBC, Lansdale ordered an airstrike bombing of the base. The airstrike bombing destroyed the entire facility and any B.O.W.s present.
↑Excerpt from BIOHAZARD REVELATIONS NAVIGATION & ART, p. 16: ファルファレルロ(中傷するもの)の名は、ダンテ・アリギェーリ著の『神曲』に登場するマレ・ブランケ(邪悪な爪)と呼ばれる12人の悪魔のうちの1人に山来する。ファルファレルロは、ハンターにさらにt-アビスを加えた改良型である。その結果、一部の水棲生物が持つような擬態能力を有し、周囲に溶け込んで透明化することを可能とした。しかし、複数のウイルスを投したことによって攻撃性が増し、従来より著しくコントロール性が劣化しているとの結果が報告されている。