He spied on strategic locations linked to Polish and NATO infrastructure, including a military equipment factory. Sergeyev arrived in Poland more than three years ago with the aim of building a career as a professional ice hockey player. Playing for OKS Zaglebie Sosnowiec in the second junior league, he failed to make it to the senior team, so in 2023, to support his stay, he began working as a food delivery boy.

Meanwhile, he was recruited via the Telegram platform by a Russian intelligence officer. He then began posting pro-Russian political content on social media, while receiving payments in cryptocurrency for his activities. His mission escalated when he became part of a group of 16 people, organized by Russia, to sabotage the transport of weapons and humanitarian aid to Ukraine. For this task, the group was to receive 10 thousand euros.