Insights from our Advisory Board members: Stefano Bandinelli. The Mostro di Firenze Case, an Italian serial killer

Published on 10th August, 2023

Insights from our Advisory Board members:  Stefano Bandinelli. The Mostro di Firenze Case, an Italian serial killer.

Continuing with our series "Insights from Our Advisory Board Members", today we present an article authored by Stefano Bandinelli.

Mr. Bandinelli served as Superintendent of the Italian National Police and former Head of the Ballistic Unit within the Forensic Police in Tuscany. He has been a collaborator of Protective Intelligence Network since its inception, offering guidance and counsel on cases handled by our office.

Throughout his career, he played an important professional role in investigating one of Italy's most notorious serial killers, The Mostro di Firenze, also known as the monster of Florence. In this piece, he shares his firsthand account of the case and emphasizes the significance of forensic ballistics.

Insights from our Advisory Board members:  Stefano Bandinelli. The Mostro di Firenze Case, an Italian serial killer.

Very few cases can rival the complexity and mystery surrounding the Monster of Florence, "il Mostro di Firenze", when it comes to criminal investigations.

Operating from the late '60s to the early '80s in the picturesque Tuscan hills, this serial killer cast a dark shadow over the tranquility of the region. However, it was the field of forensic ballistics that played a pivotal role in unraveling this enigma, ultimately leading to the identification and arrest of the culprits: Pietro Pacciani, Mario Vanni, and Giancarlo Lotti.

The heinous acts of the Monster of Florence unfolded through a series of brutal murders that shook society. The number of murders attributed to the Monster of Florence is 16, involving eight couples. Preferred victims of this criminal were couples of lovers, with murders characterized by extreme violence and genital mutilation. The apparent consistency in the methods employed made the investigation particularly challenging, while the lack of concrete evidence fueled anxiety and speculation within the public opinion.

Insights from our Advisory Board members:  Stefano Bandinelli. The Mostro di Firenze Case, an Italian serial killer.

Ballistics experts embarked on a path of detailed analysis involving the examination of crucial elements such as projectiles, casings, cartridges, and gunshot residues. Every piece of evidence was scrutinized under microscopic precision to reveal specific characteristics that could lead to irrefutable conclusions.

Specialists carefully studied the bullets recovered from crime scenes. Factors like caliber, shape, and unique deformation marks caused by friction with gun barrels were evaluated. These elements helped establish connections between seemingly unrelated homicides. Casings, with their distinctive marks left by firearms, were equally important. The analysis of firing pin impressions on casings enabled the determination of the type of weapon involved, while also revealing individual characteristics of the firearm, such as potential defects or wear patterns. This information proved crucial in linking bullets to specific weapons.

The Key Role of Forensic Ballistics

Among the array of tools available to investigators, forensic ballistics emerged as fundamental. Thorough analysis of ammunition and ballistic elements recovered from crime scenes revealed crucial links between murders that initially seemed unrelated. Ballistics experts examined bullets, cartridges, and other pieces of evidence, identifying unique details that would guide the investigation in a new direction. The pinnacle of ballistic relevance was achieved when ballistic traces from various crimes were accurately compared.

This comparison unveiled undeniable correspondences, providing crucial clues about the weapons involved. In 1993, Pietro Pacciani was apprehended based on the emerging ballistic evidence, marking a turning point in the investigation. Subsequent progress led to the identification and arrest of Mario Vanni and Giancarlo Lotti. (I compagni di Merende)

Insights from our Advisory Board members:  Stefano Bandinelli. The Mostro di Firenze Case, an Italian serial killer.

The Discovery of the .22 Caliber Cartridge

Among the fundamental ballistic assessments, the discovery of a .22 caliber cartridge in Pietro Pacciani's garden stands out.

This artifact marked a turning point in the investigation. Ballistics experts meticulously examined the cartridge, detecting every detail that could provide clues about its origin and potential use in the weapon employed in the dual homicides. Detailed analyses of the cartridge provided concrete evidence that it had been chambered in the firearm used in the dual homicides. This was made possible due to the presence of micro-striations on the cylinder of the casing, caused by impact and friction against the feed ramp at the base of the cartridge chamber entry port.

An imprint thus not provoked during the firing cycle, but during the loading cycle, specifically when the cartridge is extracted and pushed by the breech-bolt carriage into the barrel's cartridge chamber.


Further traces of micro-striations with significant analogies were observed on the upper-rear edge of the casing's rim, caused by contact with the breech-bolt carriage's pivot surface during the aforementioned cartridge pushing phase towards the barrel. These findings were utilized to advance with the arrest and charges against Pietro Pacciani and subsequently against the other suspects.

The outcomes of comparative ballistic assessments carried out on ballistic impressions present on an unexploded cartridge were fiercely contested by Pacciani's defense consultants during the trial phase. Consequently, the judges of the Superior Court of Florence (Corte d’Assise) ordered an additional Expert Examination on the cartridge which did not yield further data compared to the previous consultations and partially destroyed it, rendering a current nowadays revision of the ballistic examinations in light of new and more sophisticated instrumentation unavailable.

This latest discovery, along with a sketchpad and a soap dish that the prosecution hypothesized belonged to the victims of the 1983 crime, contributed to establishing a direct link between the suspect and the dual homicides.

Investigations revealed that Pacciani had written down a license plate number of a car belonging to a couple that frequented the Scopeti area, the site of the September 1985 crime. Additionally, he preserved newspapers and magazines discussing the Monster of Florence crimes, on whose photographic images he was accustomed to sketching a pubic area. Furthermore, Pacciani had ties to all the locations where the eight dual homicides had occurred; he had lived and worked in the two areas where the "monster" had struck most frequently: Mugello and Val di Pesa.

Insights from our Advisory Board members:  Stefano Bandinelli. The Mostro di Firenze Case, an Italian serial killer.

The case of the Monster of Florence will remain in history as an eloquent example of how ballistic analysis can solve even the darkest mysteries. As we contemplate this intricate investigative journey, it is crucial to seize the opportunity to embrace innovation in forensic ballistics, opening new doors in the art of solving complex crimes. Today, with the evolution of technologies, ballistic investigations have been enriched with cutting-edge tools. The analysis of firing pin impressions through sophisticated comparison software, the creation of global ballistic databases, and the application of advanced algorithms to identify unique traces are just a few of the innovative techniques that can be leveraged.

These tools offer the possibility of detecting connections that may escape the human eye and of accelerating investigation timelines. In the pursuit of justice, it is crucial not only to draw from the foundations of forensic ballistics but also to adopt an open approach to innovation. Investing in the ongoing training of ballistic experts and providing access to state-of-the-art technologies can open new horizons of understanding and case resolution.

Insights from our Advisory Board members:  Stefano Bandinelli. The Mostro di Firenze Case, an Italian serial killer.

In conclusion, the ballistic examinations in the case of the Monster of Florence exemplify an excellent instance of how the scientific and meticulous approach can unveil concealed truths in the most complex cases. Through the accurate analysis of projectiles, casings, and ballistic details, experts shed light on intricate connections, leading to the long-awaited breakthrough in the investigation.

The investigations into the Monster of Florence transcended Italian borders, highlighting how the application of forensic ballistics can surmount seemingly insurmountable obstacles.

Science revealed crucial connections between murders that would have otherwise remained obscure, demonstrating the importance of interdisciplinary cooperation and meticulous use of evidence. In summary, the Monster of Florence represents a dark puzzle in Italian criminal history, yet the light of forensic ballistics has illuminated the investigative path. This case underscores the power of scientific analysis in revealing hidden truths and has left a lasting mark on the global approach to combating crime.

Insights from our Advisory Board members:  Stefano Bandinelli. The Mostro di Firenze Case, an Italian serial killer.

The Monster of Florence and its resolved enigma stand as a reminder not to take anything for granted in investigations. Ballistic analysis, when fueled by innovation, can be the key that unlocks the secret behind even the most intricate cases. May its success inspire us to continue exploring, experimenting, and adapting ballistic techniques to shed light on the darkness of illegality, ensuring that truth always emerges, regardless of the challenges we may face. (SB)