A 16-year-old from Titusville has been indicted as an adult by a federal grand jury in the United States over the alleged killing of his stepsister aboard a cruise ship.

According to court records, the teenager, identified as T.H., was travelling on the Carnival Cruise Line Horizon in early November 2025 with the victim, Anna Kepner, and other family members.

The incident reportedly occurred between November 6 and 7 while the vessel was in international waters en route to Miami.

Prosecutors alleged that T.H. sexually assaulted and intentionally killed Ms Kepner during the voyage.

The Miami-Dade medical examiner later determined that the cause of death was mechanical asphyxiation.

The case was initially filed under juvenile proceedings on February 2, but remained sealed.

It was later transferred to adult court following an order by U.S. district judge Beth Bloom.

U.S. attorney Jason A. Reding Quiñones for the Southern District of Florida described the case as deeply tragic, extending condolences to the victim’s family.

Mr Quiñones stated that the government would present its evidence in court, stressing that the defendant is presumed innocent until proven guilty.

The teenager now faces charges of first-degree murder and aggravated sexual abuse. If convicted, he could receive a maximum sentence of life imprisonment.