Inside the Gory True Story of The Monster of Florence: All About the Real-Life Italian Serial Killer Who Continues to Elude Police By Emily Blackwood

Netflix has put the spotlight on another chilling serial killer.

Between 1968 and 1985, an unknown assailant dubbed Il Mostro — Italian for “the monster” — shot and killed eight couples throughout Florence, Italy. All of the victims, most of whom were in their cars during the crime, were killed with the same pistol, per CBS News. Four of the murdered were mutilated.

Though five men were accused and multiple theories have surfaced in the nearly six decades since the first killing, all the murders remain unsolved. One of the less-examined theories served as the focus for Netflix’s 2025 limited series The Monster of Florence.

The crime drama investigated the “Sardinian trail,” which speculated that Il Mostro was tied to a family of Sardinian immigrants known as the Meles. Stefano Mele, the husband of the first female victim, was convicted of her murder but was later released after other murders occurred while he was incarcerated, per Britannica.

After his arrest, police investigated several of Mele’s relatives, but all the men were eventually cleared.

Here’s everything to know about the true story behind The Monster of Florence and why police have yet to catch the real-life serial killer.

Is The Monster of Florence based on a true story?

Yes, The Monster of Florence is based on a true story. The Netflix miniseries follows the still-open case of Il Mostro, an unidentified Italian serial killer who claimed the lives of 16 people throughout the late 1960s and 1980s.

Director Stefano Sollima told The Hollywood Reporter Roma that the four-part series was based on direct testimonies and procedural documents with the hope of bringing “justice to the victims.” In doing so, he realized that not everything in the official investigation lined up.

“We reconstructed to the millimeter the crime scenes, the angle of the shots, the location of the cars and the killer,” Sollima told the outlet in February 2024. “And in some cases there were things that didn’t fit with the official versions.”

He added that the crew “ended up correcting mistakes” in their aim to maintain the historical accuracy of the case. “Our whole purpose, our maximum effort, was trying to reconstruct a historical reality,” Sollima said. “We have tried to tell all the truths, reconstructing a country, its habits and systems, its hypocrisies that have so hindered the solution of the case.”

How many people did the Monster of Florence kill?

Il Mostro is responsible for the deaths of 16 people, per CBS News. The murders began with the August 1968 killings of Barbara Locci and Antonio Lo Bianco, with whom she was having an affair, per Biography.

Though Locci’s husband, Mele, was convicted of the murders in 1970, he was later released after the culprit struck again by killing teenage couple Pasquale Gentilcore and Stefania Pettini in September 1974.

The unknown killer murdered again in 1981, slaughtering two engaged couples: Giovanni Foggi and Carmela De Nuccio, and Stefano Baldi and Susanna Cambi. Mechanic Paolo Mainardi and dressmaker Antonella Migliorini were found shot and stabbed the following June.

In September 1983, in an exception to the killer’s penchant for murdering couples, they killed two young men: German students Wilhelm Friedrich Horst Meyer and Jens-Uwe Rüsch, who were both asleep in their car at the time.

Claudio Stefanacci, a student, and Pia Gilda Rontini, a bartender, were shot and stabbed in Stefanacci’s car the following July.

The last of the known murders took place in September 1985, when French couple Nadine Mauriot and Jean Michel Kraveichvili were shot and stabbed while on a camping holiday. Prosecutors later received a package from the killer with a taunting letter and a part of Mauriot’s remains.

Though police eventually determined that the same .22-caliber Beretta was used in every double homicide, it was never found, per The Hollywood Reporter.

Was anyone charged in the Monster of Florence murders?

Five men were named suspects, and three were found guilty in the Il Mostro murders, per CBS News. However, all were later cleared because another murder had taken place while they were incarcerated.

The first suspect was Pietro Pacciani, a farmer and convicted murderer and rapist. Prosecutors believe he had committed the murders with several friends, including Mario Vanni and Giancarlo Lotti, who were found guilty of killing four of the eight couples.

Though Lotti had confessed, lawyer Valter Biscotti, who represents Estelle Lanciotti, the eldest daughter of victim Mauriot, told CBS there were “inconsistencies” in his story and that no trial so far had gotten “to the whole truth.”

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Though Pacciani was sentenced in 1994 to life in prison for the killings of 12 of Il Mostro’s 16 victims, he was cleared by an appeal court two years later. The ruling was later overturned, but Pacciani died of a heart attack in 1998 before his retrial. Vanni and Lotti have also died.

Another highly popular theory is that Il Mostro and the Zodiac Killer — who is believed to have killed five people in California between 1968 and 1969 — are the same person. However, that connection has never been proven.

What is the latest in the Monster of Florence case?

In 2022, the families of three of Il Mostro’s victims formally asked prosecutors to take another look at the case. Biscotti told AFP, per CBS News, that they believe some elements “were wrongly overlooked” in old case files.

“We want a fresh look at a lead concerning a suspect named in an old police file who was never investigated properly, as well as DNA found on anonymous letters,” Biscotti said.

The suspect in question is Giampiero Vigilanti, another friend of Pacciani’s. During a search of his home in the 1980s, police found newspaper clippings of the killings and bullets of the same make used in the murders.

Biscotti said that he wants police to reopen the case into Vigilanti, now in his 90s, and to compare his DNA to the unidentified male sample.

In 2024, CBS News reported that the same DNA was found on evidence taken from three different crime scenes in the Il Mostro murders. The sample doesn’t match any of the victims or anyone convicted in the case.