The Florida teenager accused of killing his stepsister aboard a Carnival cruise ship last year has been taken into the custody of the U.S. Marshals and will be held behind bars ahead of his upcoming trial.The 16-year-old suspect, identified in court filings by his initials as "T.H.," was ordered to report to the federal courthouse in Tampa earlier Monday morning, where his family would deliver him to the U.S. Marshals' custody.T.H. was indicted as an adult by a federal grand jury on charges of murder and aggravated sexual abuse in the Nov. 2025 killing of his stepsister, Anna Kepner. He has pleaded not guilty.Popular ReadsThis is a developing story. Please check back for updates.