Nathan Carman said his boat took on water and suddenly sank. The 22-year-old survived and was rescued at sea, but his mom, Linda, was nowhere to be found and presumed dead. As officials investigated Nathan's story, they began to doubt his account of the events that unfolded out at sea. They suspected he may have purposefully sunk the boat and killed his mother, whose body was never recovered. Nathan denied the allegations, insisting the sinking was an accident. Now, in a new 20/20 investigation, detectives reveal how they worked on a case that spanned the Northeast and shed light on a family they believe was fractured by wealth. 20/20 "Family Lies?" premieres Friday, April 4th at 9/8c on ABC and streaming the next day on Hulu. Tap the LINK IN 20/20's BIO TO READ NOW. #TrueCrime #Investigation #LostAtSea #Mystery