Michel Peiry was born on February 28, 1959, in Romont, Switzerland.

On September 1, 1981, Michel Peiry's first crime was reported when he met a young Canadian named Sylvestre in the United States. Shortly after their meeting, Sylvestre disappeared. Peiry confessed to the murder but later retracted his statement before admitting it once again.

On February 4, 1984, Peiry killed a young man named Frédéric in the Annecy region of France. The following year, in June 1985, he murdered his only known female victim, a woman named Anne-Laure or possibly Anne-Fleur, in Saintes-Maries-de-la-Mer, Camargue.

On May 7, 1986, he took the life of a young man named Cédric in Albinen, Switzerland. In July of that year, Peiry traveled to several European countries and claimed to have murdered a man named Silvio in Rijeka, Croatia, although he later retracted this confession.

On the night of August 14 to 15, 1986, he killed a young hitchhiker named Fabio V. in the canton of Ticino. In November 1986, he attacked Yves Ath in Neuchâtel, who thankfully survived despite being severely injured.

In March 1987, the burnt remains of a young man named Vincent were discovered, and there were similarities to the methods used by Peiry, but no direct evidence linked him to this case.

On April 16, 1987, Peiry killed another young man in the Como region of Italy, admitting to the crime before later retracting his confession. His last attack was on April 24, 1987, when he assaulted a young man named Thomas, who survived the encounter.

Peiry was arrested on May 1, 1987, while stationed for military service in Bern. He was eventually sentenced to life imprisonment. In the days following his arrest, there were inquiries into the disappearance of 19-year-old Patrick Gache. However, no evidence connected Peiry to this case.

Peiry made requests for parole in 2002 and again in 2009, but both were denied.