Disturbing new twist in Anna Kepner 's death aboard a Carnival Cruise ... the feds say her 16-year-old stepbrother raped her before murdering her on their family vacation. Anna's stepbrother has been indicted as an adult by a federal grand jury and charged with first-degree murder and aggravated sexual abuse ... according to federal prosecutors in Florida. The feds only identify Anna's stepbrother by his initials T.H. , and say he's facing a maximum sentence of life in prison if convicted.