Teen accused in cruise ship killing of stepsister pleads not guilty

A Florida teenager accused of killing his 18-year-old stepsister, Anna Kepner, aboard a Carnival cruise ship has pleaded not guilty in Miami federal court, moving the case into the next stage of a closely watched federal prosecution.

Court records and news reports say the teen entered the plea on April 21, 2026, and waived his appearance at the hearing. He is being prosecuted as an adult by a federal grand jury on charges that include murder and aggravated sexual abuse, and prosecutors are seeking detention as the case advances.

Kepner was found dead in November 2025 in a cabin aboard the Carnival Horizon during a family cruise vacation. One report said the Miami-Dade Medical Examiner ruled the death a manual asphyxiation. Kepner, a senior at Temple Christian in Titusville, Florida, had been aboard the ship with relatives when she died.

The case has drawn unusual attention because it unfolded on a cruise ship, where jurisdiction can raise questions that do not arise in a typical local homicide investigation. In this case, the federal court in Miami is handling the matter, underscoring how serious crimes at sea can move into the federal system rather than stay in state court.

That federal route also helps explain why prosecutors can pursue charges that do not always mirror the course of a state case. When a death occurs in a setting tied to maritime jurisdiction, federal prosecutors may bring their own counts, and separate proceedings can follow if different laws are implicated. Here, the prosecution is focusing on both the killing allegation and the sexual-abuse charge while pressing to keep the defendant in custody.

The teen’s age has added another layer of public interest. Even though he is described as a teenager, published coverage says he has been indicted as an adult in federal court, a step that places him in the adult criminal system for one of the most serious types of cases the courts handle. The waiver of his appearance at arraignment kept the hearing brief, but it did not change the stakes.

For Anna Kepner’s family, the case remains centered on a loss that began as a cruise vacation and ended in federal court. For prosecutors, the next stages will focus on detention, pretrial motions and the government’s effort to prove the charges before any trial can begin.