Mateo Banks

Although the family was originally from Chascomús by 1922 they owned two cattle ranches on the outskirts of Azul, referred to as el "Trébol" y la "Buena Suerte."[2] While Mateo Banks lived away from the ranches in the city, on the afternoon of April 18 he traveled to la Buena Suerte where his brother Dionisio was staying with his daughter Sara (Sarita). After killing his brother with a Winchester rifle he then beat Sara with the rifle and threw her down a well. He then fired into the well, killing her. When one of the ranch's peons, Juan Gaitán, arrived he was also gunned down.

Banks then traveled five kilometers to el Trébol where he encountered another laborer named Claudio Loiza. After convincing Loiza that Dionisio was sick and needed aid, they began traveling back to la Buena Suerte. Partway between the ranches Banks shot Loiza to death and hid his body.[1]

Traveling back to el Trébol Banks spent the rest of the day with those staying there; namely his sister María Ana, his brother Miguel, Miguel's wife Julia, Gaitán's daughter María Ercilia, and Dionisio's other daughters Cecilia and Anita.[2] At night he awoke his sister, convinced her to come to la Buena Suerte to check on Dionisio, and killed her along the way. He returned to el Trébol, woke up Miguel, Julia, and fifteen-year-old Cecilia and shot them each to death. He left five-year-old Anita and four-year-old María Ercilia alive and locked in a room.[1]

According to Banks he came upon Gaitán and Loiza after they had attacked his family. Banks then shot Gaitan and wounded Loiza,[2] who shot Banks in the foot. This "bullet hole" in his boot was later revealed to have been made with an awl.[1] He claimed he then spent time with Miguel as he lay dying, though the autopsy showed that Miguel had died instantly.[3] Eventually, the prosecution tied Banks to the purchase of the ammunition and to an attempted poisoning of his family earlier on the day of the crime. He also confessed at one point, but later claimed it was through torture by the authorities.[1]

In the course of the investigation it was revealed that Banks had lost his fortune and was on the verge of destitution, even after having sold part of his inheritance to his siblings. He had also sold large amounts of cattle that didn't belong to him after forging Dionisio's signature.

The prosecutor concluded that Banks wanted to a) conceal his past crimes from the family and b) inherit the fortunes of both María Ana and Miguel. He couldn't attain Dionisio's fortune due to Dionisio's wife still being alive and away in a mental institution. This (in addition to her youth making her an unreliable witness) explains why Anita was not killed. Since Dionisio would still have an heir (his wife) it was not profitable. Banks also spared María Ercilia because her death would have contradicted his story that her father was one of the perpetrators.[1]

Banks had two trials, both of which ended with a sentence of life imprisonment. At the second trial famed lawyer Antonio Palacios Zinny tried to garner sympathy with the jury by having Banks poison himself in front of them with a (non-fatal) dose of cyanide. Banks wouldn't go through with it. Despite being sentenced to life in prison he was released in 1949. He moved to Buenos Aires under an assumed name and died later that year at the age of 77.[1]