Fernando José Báez Sosa was born on 2 March 2001 in Buenos Aires, the only son of Silvino Báez and Graciela Sosa, both Paraguayan immigrants. He grew up in the Recoleta neighborhood, attended the Marianistas de Caballito high school on scholarship, and went on to study law at the University of Buenos Aires. He was in a relationship with fellow law student Julieta Rossi.
On 16 January 2020, Báez Sosa traveled to the seaside resort town of Villa Gesell with a group of high school friends and his girlfriend, staying at the Hola Ola hostel. In the early hours of 18 January 2020, the group went to the Le Brique nightclub. A verbal altercation broke out around 4:30 a.m. after one of Báez Sosa's friends accidentally bumped into a member of another group, leading nightclub security to eject both groups. Shortly after 4:44 a.m., while Báez Sosa and his friends waited outside for the rest of their group, several members of the other group attacked them. Báez Sosa was punched and kicked until unconscious, sustaining blunt head trauma; the beating lasted less than a minute. Prosecutors described the attack as coordinated, with some assailants striking Báez Sosa while others blocked his friends from intervening. Part of the assault was filmed by one of the attackers on a cellphone.
Following the attack, the group returned to their rented accommodation, changed clothes, and were reported by witnesses to have been boasting about the incident; a photograph of several of them smiling, taken about 20 minutes after the beating, later circulated widely. All ten members of the group were detained by provincial police later that morning. Báez Sosa's autopsy determined he died of neurogenic shock with internal bleeding from multiple blows, making it impossible to identify a single fatal strike. Eight men — Máximo Thomsen, Ciro Pertossi, Luciano Pertossi, Lucas Pertossi, Matías Benicelli, Enzo Comelli, Blas Cinalli, and Ayrton Viollaz — were charged with aggravated premeditated homicide. Two other men initially implicated, along with a third who was a minor at the time, were not charged due to insufficient evidence, and remaining charges against two of them were dropped by April 2021.
In the immediate aftermath, the accused had falsely implicated an acquaintance, Pablo Ventura, who was briefly detained before being released and cleared of any involvement.
The trial of the eight charged men began on 2 January 2023 before the Tribunal Criminal N°1 de Dolores, with roughly 130 witnesses expected to testify. On 6 February 2023, the tribunal found all eight guilty of homicide doubly aggravated by premeditation and ambush. Thomsen, Ciro Pertossi, Luciano Pertossi, Benicelli, and Comelli were designated co-perpetrators and sentenced to life imprisonment; Lucas Pertossi, Cinalli, and Viollaz were designated secondary participants and sentenced to 15 years in prison. The case drew extensive national and international attention, including condolence messages to the family from Pope Francis and then-President Alberto Fernández, and prompted public discussion in Argentina about violence associated with rugby culture.