Complex sentence: Author Howie Carr writes that Bulger had been an off-the-books informant since his teenage years and that, like Flemmi, he had been recruited by Special Agent H. Paul Rico.
Split into simpler sentences: Author Howie Carr alleges that Bulger had been an off-the-books informant since his teenage years. Carr further claims that, like Flemmi, Bulger had been recruited by Special Agent H. Paul Rico.