As judge and mayor over crime in Lima in 1781, he led the case against Túpac Amaru II, writing the judgment which condemned to death by hanging him and several of his followers, as well as penalties in prisons in Africa, Callao and Valdivia for many others.
de Rezabal y Ugarte also led other causes connected with this case, including another trial against Manuel Antonio Figueroa, called El Incognito.
This last position was not occupied at first as it was intended for the complicated trial prompted by the collapse which occurred at the mine in Huancavelica that year, killing 200 people.
During his brief four-month governing he continued the work of Tajamares del Mapocho, originally initiated by the outgoing governor Ambrosio O'Higgins.
According to Diego Barros Arana it was de Rezabal y Ugarte who planted the poplar grove that ran along these river defenses, which was the only public promenade in the city of Santiago for over 30 years.