What would you do if your brother was a pedophile but...?

What would you do if your brother was a pedophile but you had no proof? My brother is now in his 50s. He was introduced to homosexuality by out of all people, his psychiatrist. They had sex with under age boys several times between the two of them. Although I only caught him in the act once when he was about 24, I promptly grabbed is lover by the hair and thew him out of the house naked. Back then I did not tolerate any type of homosexual behavior. I have since completely changed my out look about homosexuality but not pedophilia. Iam not gay but I think it is just fine for people who are. I've only seen him run around with teen age boys his whole life. His psychiatrist is now dead but from what I hear he trolls the internet constantly looking to meet new teen aged boys. So I guess my question really is if none of the boys report him, how can anyone make it stop?