A native of Pian Castagnaio, Barzellotti studied medicine at the University of Siena, where he had the chance to attend the lessons of Paolo Mascagni (1755-1815). After graduating in 1792, he practised the profession until 1800, the year in which he was appointed to the Chair of Surgical Institutions at the University of Siena. He expended great effort in combatting the epidemics that recurrently struck the Livorno and Grossetano zones in the early years of the 19th century. The fruit of his observations were the Polizia di sanitą per evitare i contagi, conservar la vita, la sanitą e gli interessi dei popoli e delle nazioni [Healthcare police to avoid contagion, conserve life, health and the interests of the people and the nations] (1806) and, of greater interest from the viwpoint of social medicine, Dell'influenza della povertą sulle malattie epidemiche e contagiose [The influence of poverty on epidemics and contagious diseases] (1839). Considered one of the fathers of modern forensic medicine in Italy, he became professor of this discipline at the University of Pisa in 1810. Testifying to his commitment in this sector is his monumental work Medicina legale secondo lo spirito delle leggi civili e penali veglianti nei governi d’Italia [Forensic medicine according to the spirit of the civil and penal laws in force in the governments of Italy] (1818).