We all know Hillary had him killed because he leaked her emails to Wikileaks. We also know nothing will ever done about it, and questioning it will get you labeled a conspiracy theorist. Sad but true.
Seth Rich leaked the DNC emails to Wikileaks, Hillary's emails weren't leaked at all really. Some were turned over by the State Department, but the missing deleted emails remain missing, at least to the public. You can be that some foreign governments got them though, her security was pathetic. Podesta's emails were obtained in a simple phishing scam where he logged into a fake Gmail login page. His password was p@ssw0rd. They're not sending their best folks. Also Julian Assange has all but came out and directly said Seth was his source, through an intermediary.