Luigi Chiatti was born on February 27, 1968, in Narni, Italy. His birth name was Antonio Rossi. His mother, Marisa Rossi, was a young maid who could not care for him. Shortly after he was born, she abandoned him. Because of this, Antonio spent the first few years of his life in an orphanage near Narni.

When Antonio turned six years old, his life changed. He was adopted by Ermanno Chiatti, who was a physician, and his partner, Giacoma Ponti. They lived in Foligno, Italy. On June 13, 1975, his adoption became official, and his name was changed to Luigi Chiatti.

On the afternoon of 4 October 1992, four-year-old Simone Allegretti disappeared in the countryside between Foligno and Bevagna. His body was discovered two days later along an escarpment, close to the area where he went missing. Just before the discovery, a note was found in a telephone booth at the railway station in Foligno. This note claimed responsibility for the murder and provided details about the location of the body and the clothing that Simone was wearing. It also indicated that the murderer was willing to kill again.

In response, the police in Perugia set up a toll-free number and issued a note to the killer. On 13 October, a man identifying himself as the "Monster of Foligno" called the toll-free number multiple times. This led the police to investigate Stefano Spilotros, a Lombard real estate agent. However, inconsistencies in his alibi and testimonies from his friends and relatives excluded him from being guilty. The intense public panic surrounding the case led to other tragic events, including the suicide of a young worker from Macerata, who claimed he was the monster in a note he left behind.

On 7 August 1993, Chiatti struck again, killing 13-year-old Lorenzo Paolucci. Lorenzo’s body was found just 30 feet from Chiatti's villa. The police followed the evidence to Luigi Chiatti, and he was captured. Chiatti confessed to both murders within a short time.

On 1 December 1994, the trial against Chiatti started for the murders of Simone Allegretti and Lorenzo Paolucci. On 28 December, he was sentenced to two life sentences.

However, on 11 April 1996, the Court of Appeal of Perugia changed his sentence, declaring him semi-mentally ill and reducing his punishment to 30 years of imprisonment. This decision was upheld by the Supreme Court of Cassation on 4 March 1997. During the court proceedings, a witness from an orphanage testified that both he and Chiatti had been sexually abused by a priest.

Chiatti served his sentence in the prison of Prato, Tuscany. He asked for early release twice, but these requests were denied. In June 2009, there were rumors that he had been released from prison for a few hours, but his lawyers denied this.

On 3 September 2015, Chiatti completed his prison sentence but was required to stay for at least another three years in a Rems facility in Capoterra, Sardinia. His stay there was extended twice by the Surveillance Court of Cagliari, in 2018 and 2020, after evaluations indicated he remained a danger to society.