He was known as the man who armed the Black Panther Party with guns and weapons training. With his trademark sunglasses and mustache, Richard Masato Aoki was a militant with ties to radical groups in the 1960s. But new information suggests he was also an FBI informant. Journalist Seth Rosenfeld joins us to talk about Aoki’s hidden life and other secrets from his new book, “Subversives: The FBI’s War on Student Radicals, and Reagan’s Rise to Power.”