- It's entirely possible for someone to hide in plain sight, with a respectable job which involves wearing a suit (they said he'd been a private detective after leaving the police force, so it could be that). Faking his death means the police wouldn't be looking anyway.
Head Scratchers / Frequency
Ok, even accepting the premise as a whole, why does Shepherd in the future look the same in the final scene as he did the first time John met him? They'd changed the timeline so that he had to fake his death and go on the lamb 30 years earlier. He shouldn't be clean-shaven, and wearing a nice suit. He probably just spent 30 years in the criminal underworld.