Bruno Borges story on reddit.
Daily Mail article on Borges.
El Globo's story on Borges.
An update on the Bruno Borges disappearance, connecting it to Cicada #3301, can be found here.
I have no idea what to make of it all. It's awfully neat handwriting for someone who's experiencing mental problems, which suggests that it's an art project or part of the Cicada scavenger hunt.
Update: It may all have been part of a book marketing scheme.
"On the day Bruno left, he went to the notary's office and recorded the contract. So, for us, it is very conclusive that it was not a disappearance whatsoever, it was in fact a conscious plan of remoteness, and the contract shows that there is a deadline for disclosure of these books, deadline for publication, percentage allocation for those who helped him, in the case , These three people who helped him right away. For us, this is very clear, "said Alcino Júnior, the delegate of the case, to the G1 .
Update 6/11/17: More from the police investigation here.