Complex sentence: The tally sheets and passenger records showed that 409 slaves survived the passage to arrive at Jekyll Island, which was owned by John and Henry DuBignon, Jr., who conspired with Lamar.
Split into simpler sentences: The tally sheets and passenger records showed that 409 slaves survived the passage. They were landed at Jekyll Island, which was owned by John and Henry DuBignon, Jr., who conspired with Lamar.