Brazil is a huge country and if anything could benefit from having big immigration rates.
And how would that relate to a possible weakness in the system which permits exploitation of gov aid by immigrants?
You can never stop these kinda things tho, a normal person can turn into a complete maniac due to some happening..
It is the wonders of modern society...
Plastic surgery, making money in business firm, attending z0mg high society events have become more important than looking after your own children.
Hiring someone to look after your children instead of looking after them yourself, thinking they'll do the parent role. Most cases the nanny just does what is needed to not get fired and doesn't really care if the child needs support. Or in cases where government provides that, leave children all day in school and if something goes wrong it is totally the school's fault.
If you grab data on school shooter cases, you'll notice that all of the backgrounds are related to lack of parental attention/care...