Complex sentence: Oswald visited the Dallas FBI office about 2 to 3 weeks before the assassination, asking to see Special Agent James Hosty; told Hosty was unavailable, Oswald left a note that, according to the receptionist, read: Let this be a warning.
Split into simpler sentences: Oswald visited the Dallas FBI office about 2 to 3 weeks before the assassination, asking to see Special Agent James Hosty. When he was told that Hosty was unavailable, Oswald left a note that, according to the receptionist, read: Let this be a warning.