Brazilian Call of Duty: Mobile eSports player Guilherme Alves Costa has been arrested after he allegedly stabbed and killed his rival.

As the Times writes, 18-year-old Alves Costa has admitted to killing 19-year-old fellow Call of Duty: Mobile gamer Ingrid Oliveira Bueno da Silva in his Sao Paulo Home. She was there for part of a competitive tournament for the game, and other gamers alerted authorities after Alves Costa reportedly shared graphic videos of her dead body through WhatsApp.

Oliveira Bueno da Silva’s team Fantastic Brazil Impact (a.k.a. FBI E-Sports) released a statement on her murder, calling her an “extraordinary person whom we will remember every day.” She was known online as SOL.

“You’re thinking it’s ink or that it’s edited or something, but it’s not,” Alves Costa allegedly said in group messages. “I really killed her, got it? I’ve got a book, too. I asked some people to share it. I hope you read it. It contains some truths.”

The book he’s referring to is a 52-page manifesto in which he explained why he committed murder. He said the lack of direction in his life, his inability to connect with others, and being tired of life were the biggest contributing factors.

He initially fled the scene, but when his brother returned home he discovered Oliveira Bueno da Silva’s body on the floor. Alves Costa reportedly called his family and informed them he intended to take his own life, but his brother convinced him not to do it. When asked by police officers why he committed murder, he replied, “Because I wanted to. … I know the seriousness of this situation.”

He additionally told investigators that Ingrid had “crossed [his] path.”

Alves Costa played for the team Gamers Elite, but the team has claimed they never met him.