BOULDER — Following the suicide of the boy who authorities said was the ringleader, Boulder Valley schools have expelled or disciplined a group of students who used a Nazi-themed Facebook chat to call for the deaths of Jews, African-Americans and Mexicans. Those who monitor hate groups say it appeared to be much more than simple youthful rebellion, calling it a product of a dangerously overheated political environment that has also seen an increase in bullying and intimidation of fellow students. Approximately 15 students made up a Facebook group called the “Fourth Reich’s Official Group Chat” and talked about starting a movement to kill minorities and other groups, according to a Boulder police report.