Sergei Kashfulgayanovich Martynov was born on June 2, 1962, in Nyazepetrovsk, a town located in the Chelyabinsk Oblast of the Soviet Union.

In 1992, Sergei Martynov was arrested on suspicion of raping and murdering an unidentified woman. He was convicted for this crime. After nearly 14 years in prison, he was released in 2005. Soon after his release, he attempted to rape a young girl at knifepoint in Kemerovo but the victim survived. This incident placed him on a wanted list.

In June 2007, Martynov murdered a woman in Glazov, Udmurtia. He dismembered her body after the crime. The following month, he raped an 8-year-old girl in a village called Vyazovka, located in Nizhny Novgorod Oblast. In May 2008, he killed a man during a robbery. The next month, he murdered an elderly woman in a forest and again dismembered her body. In November 2008, he committed another murder in Oryol Oblast.

In August 2010, he raped and killed a 70-year-old woman in Bashkortostan. He left a note after this crime, expressing that he was not afraid of the police and that he would be in Chelyabinsk at noon. Later that year, in late 2010, he killed another woman in Voronezh Oblast.

Martynov was arrested on November 18, 2010. The police caught him after he activated a mobile phone that he had taken from one of his victims. He did not resist arrest and said that he wanted to be caught. Prosecutors stated that he committed violent crimes across at least ten regions in Russia. He was charged with multiple murders and assaults, including violent acts against two young girls. He reportedly mutilated many of his female victims.

On May 23, 2012, details of his case were publicly shared. Martynov faced charges for intentional injury, murder of several people, and sexual violence. He acted boldly and left evidence at the crime scenes. Martynov claimed that his killings were for a "cleaning of society." While awaiting trial, he expressed a desire to kill another inmate because he was bored. In the end, he was convicted for eight murders and sentenced to life in prison.