New details are emerging in the death of Anna Kepner aboard a Carnival cruise ship after a number of documents were unsealed in federal court

Anna Kepner.

Anna Kepner.Credit : Anna Kepner/Instagram

The stepbrother of Anna Kepner “engaged in … the most serious, egregious, and violative crimes one person can inflict upon another,” prosecutors wrote in a motion asking the judge to revoke his pretrial release, a copy of which was obtained by PEOPLE.

The 16-year-old boy, identified in court documents as T.H., was indicted by a federal grand jury on charges of murder and aggravated sexual abuse on Monday, April 13, and will now be tried as an adult.

As a result, he is facing the possibility of life in prison if convicted on either charge as opposed to being released at the age of 21, which he would have been if he were to be tried as a minor and convicted on those same charges.

Cozumel, Mexico, Cruise Port Pier, arriving Carnival Horizon cruise ship.

Carnival ‘Horizon’.Jeffrey Greenberg/Universal Images Group via Getty

The grand jury states in the superseding indictment that T.H. “did knowingly and unlawfully perpetrate” the “willful, deliberate, malicious and premeditated killing of [Kepner] with malice afterthought.”

Further, the grand jury states that this occurred during the “perpetration” of an “aggravated sexual abuse.”

That “aggravated sexual abuse” is detailed in the indictment as a “sexual act,” during which T.H. penetrated Kepner “by the use of force.”

At the time of Kepner’s death, the 18-year-old was sharing a room with her stepbrother and 14-year-old half-brother during a family vacation on Carnival Cruise Line’s Horizon in November 2025.

The indictment states that both the murder and sexual abuse occurred “on or about Nov. 6, 2025.”

In a motion requesting an alibi from the defense, prosecutors place the time of the offenses as being between 7:30 p.m. and 9:30 the following morning.

Kepner’s body was found under her bed in the cabin, and the Miami-Dade Medical Examiner’s Office determined her cause of death to be mechanical asphyxiation.

T.H. made his initial court appearance in a Miami federal courtroom back in February, but was then released back into the custody of his uncle, a law enforcement source previously told PEOPLE.

He is currently splitting his time between his father and his aunt because his uncle is away at a religious retreat this week, according to court documents.

His mother, Shauntel Kepner, and her husband, Anna’s father Chris Kepner, voiced their anger about the decision to release T.H., saying: “At this time, it is deeply painful and disturbing to our family that the person responsible is able to walk freely. This reality adds to our grief and outrage.”

That statement continued: “It is devastating to know that while we live every day with the loss of our child, the individual responsible has not yet been fully held accountable.”

That decision is set to be revisited now that T.H. is being tried as an adult, according to the filing from prosecutors, but a date for that hearing has not yet been added to the court docket.

Anna Kepner.

Anna Kepner.Anna Kepner/Instagram

Prosecutors have also revealed alleged evidence so far collected in the case in three discovery orders filed in court.

This includes: “a written statement by the defendant,” DNA found at the crime scene, data extracted from the cellular telephone of a person identified as C.K., and reports from both federal and local law enforcement agencies.

One thing prosecutors do not have, according to these filings, is “any latent fingerprints or palm prints that have been identified by a government expert as those of the defendant.”

T.H. is being represented by a team of federal public defenders who did not respond to PEOPLE’s request for comment.