Mastro Titta shortened the lives of many people (as well as the people themselves) but he was himself extraordinarily long lived -- his career as "il carnefice", the "slaughterer" or "meat maker", started in 1796, and he took his last head in 1864. He worked at various Roman venues over the years: at the bridge in front of Castel Sant'Angelo, in Campo di Fiori, at Piazza del Popolo, and, most often, in Via de' Cerci in the old Forum Boarium, appropriately enough, the ancient Roman abattoir and meat market. On retirement, he published his memoirs -- he apparently kept detailed notes of the proceedings.
Mastro Titta was barred from entering "the city" (he lived in Trastevere) except for those times when his services were desired. Ostensibly, this was for his own protection, to guard him from the attentions of vengeful relatives, but also, undoubtedly, there was fear, superstition, and distaste for his part-time occupation. On most days he was a simple "umbrella painter", hand-painting parasols for the tourist trade. When Mastro Titta did don his cape and "cross the bridge", it was a signal that a head was soon to fall. Victims, persons already condemned for a variety of offenses, were always available.
The news that he was about would quickly spread and a crowd would gather at the appointed place. Executions were immensely popular, and it was traditional for fathers to bring their young sons to see first-hand the consequences of crime. In one of his most famous populist sonnets, the poet Giuseppe Gioacchino Belli memorializes such a visit and the preemptive slap received by the boy witness at the instant of the execution (see the link below). Following the time honored tradition, the head would be displayed immediately to the crowd and then exhibited indefinitely on a pole in some public spot.
Descriptions of his work, besides those that he himself penned have come down to us, and the most famous is that written by Charles Dickens after an 1845 execution which he witnessed.
Mastro Titta's memoirs are only in Italian, don't appear to be on the Internet, and are even hard to find in print. The Dickens account is on the Internet at http://www.geocities.com/Paris/Arc/5319/dickens.htm and Belli's sonnet is at http://www.geocities.com/Paris/Arc/5319/dickens.htm#Belli (lower down on the same page.)
A description of Mastro Titta's life and work is at http://www.geocities.com/Paris/Arc/5319/roma-c12.htm
P.S. 1: Contrary to popular belief, Dr. Joseph Ignace Guillotin did not invent the mechanical monster that bears his name. Earlier versions were used in Halifax, (England), Edinburgh, Milan, and Nuremberg as early as 1286. For details, go to http://www.geocities.com/CapitolHill/6142/guillotine.html
P.S. 2: Masto Titta's Christian name, Giovanni Battista, was ironically appropriate. John the Baptist was, of course, famously beheaded at the behest of Salome, and the Archconfraternity that consoled the condemned and their families was headquartered in the Church of San Giovanni Battista Decollato (the "separated", i.e., beheaded) near the Foro Boario.