Anna Kepner, an 18-year-old high school student, died aboard the Carnival Horizon cruise ship during its return to Miami from a Caribbean trip.Authorities found her body hidden under a bed, and preliminary forensic results suggest she was strangled using a "bar hold," with no drugs or alcohol involved.The FBI is investigating the death, focusing on Anna's 16-year-old stepbrother as a suspect, while custody disputes involving the boy's parents continue.