Nikolai Aleksandrovich Ageyev was born on May 1, 1974, in Kurgan, Kurgan Oblast, Russia.

In 2006, while serving time in prison, Nikolai Ageyev killed his cellmate. He was convicted of murder and received an additional 16 years on his sentence. In 2018, he was released on parole for good behavior, but he had nowhere to go. He moved to Yekaterinburg and became a vagrant.

During August 2018, Ageyev started a crime spree. On August 17, he went to the apartment of an elderly woman and attacked her. He choked her and then struck her multiple times with a hammer and an axe. He stole 13,000 rubles before fleeing the scene.

After this murder, he fled to Chelyabinsk, where he committed more robberies. He targeted food vendors at night, attacking them with a metal wrench. Over the course of a month, he stole thousands of rubles from different vendors. On September 8, he assaulted a salesperson at a store, seriously injuring her. On September 10, he attacked a vendor at a kiosk, leaving her with grave injuries.

On September 11, Ageyev killed again in Kamensk-Uralsky. He befriended a 36-year-old man and went to his apartment, where he also attacked the man's 10-year-old stepdaughter. After assaulting the man, Ageyev sexually abused the girl and later drowned her in a bathtub. He stole 19,000 rubles from the apartment and left the scene.

He was arrested on September 13, 2018, after authorities recognized him from surveillance footage. While in detention, he confessed to his crimes. His trials led to multiple charges, resulting in a life sentence on September 18, 2019.

In 2024, Ageyev killed again in prison. After developing a conflict with his cellmate, he attacked him with a piece of cement. He struck the man nearly 40 times, leading to the victim's death. Ageyev claimed he did it because he disliked him. He was found guilty of this murder and received a second life sentence.