Complex sentence: As a result, Byck and his assassination plot remained relatively unknown until a movie based on his story, "The Assassination of Richard Nixon", was released in 2004, starring Sean Penn as Bicke (the spelling was changed to avoid offending living relatives).
Split into simpler sentences: As a result, Byck and his assassination plot remained relatively unknown until a movie based on his story, "The Assassination of Richard Nixon", was released in 2004. The film starred Sean Penn as Bicke (the spelling was changed to avoid offending living relatives).