Kiryl Kazei is from Minsk. Before the arrest, he worked for a computer equipment sales company. He is married and has two children aged 7 and 10.

On October 27, 2020, a video went viral on social media of a BMW driver beating a man on the road. Earlier, the man was waving his white-red-white flag, and the driver's violent reaction was apparently casued by his political position (later the attacker argued that the incident was not related to politics). After the video became viral, the attacker's address and phone number were leaked online. According to the investigation, three Minsk residents decided to punish the man by puncturing the tires of his car. On the night of October 28, 2020, they came to his neighborhood, but on the way two of them (Kiryl Kazei and Yury Siarhei) were arrested by the riot police, and another participant managed to escape and is now wanted. During a personal search, an air pistol without bullets and a cylinder were confiscated from Kazei, and a homemade knife was confiscated from Siarhei, which the examination later called blade weapons. The next day, when searching Kazei's car, flags, leaflets, fireworks, laser pointers, a hand grenade, and 58 rounds of ammunition were found. The search of the car was shown in a news story on state-owned TV channels.

Kiryl Kazei and Yury Siarhei were charged under three articles of the Criminal Code: 'preparation for committing particularly malicious hooliganism' (Part 1 of Article 13 and Part 3 of Article 339 ), 'preparation for intentional destruction or damage to property' (Part 1 of Article 13 and Part 2 of Article 218), and 'illegal storage of ammunition' (Part 3 of Article 295). They were in custody since November 13, 2020.

Kazei and Siarhei pleaded not guilty in court. Kiryl Kazei told in detail about his arrest, the violence committed by the riot police, the threats and harassment he faced in the police department.

On March 31, 2021, in the Zavodski District Court of Minsk, Judge Anzhela Kastsiukevich sentenced Kiryl Kazei to 7 years of imprisonment in a medium-security penal colony and Yury Siarhei to 6 years in a medium-security penal colony, that is the very punishment requested by the prosecutor.

The political prisoner is serving his sentence in penal colony #3 in Viciebsk. According to human rights defenders, the political prisoner faces pressure from the administration. They often place him in a punishment cell and keep him there for several months a year.