A Florida 16-year-old is being charged as an adult in the sexual abuse and murder of his stepsister on a Carnival cruise ship last year, authorities said Monday. The teen, T.H., of Titusville, is charged with first-degree murder and aggravated sexual abuse in the killing of Anna Kepner, the U.S. Attorney's Office for the Southern District of Florida said. Kepner, 18, was found dead, asphyxiated, on Nov. 7 under the bed in a cabin the siblings shared on the Carnival Horizon cruise ship while on vacation with Kepner’s family, records showed.