MIAMI — A teenager charged with killing and sexually assaulting his 18-year-old stepsister aboard a Carnival Cruise ship has been taken into custody following a federal judge’s decision to revoke his pretrial release after he was charged as an adult.

Timothy Hudson surrendered Monday at the federal courthouse in Tampa, according to the U.S. Attorney’s Office in Miami. The detention order, signed last Wednesday by U.S. Magistrate Judge Edwin Torres, was kept under seal until its public release on Monday afternoon. The order required Hudson to report to U.S. Marshals that morning.

Hudson, who was 16 at the time of the alleged crimes, had initially been allowed to remain out of custody after a February hearing, under conditions that included living with an uncle and electronic monitoring. However, after the case was moved to adult court in April, prosecutors requested that Hudson be detained due to concerns about community safety. Judge Torres agreed, ruling that the decision on detention should be handled as if Hudson were an adult, although he will be held in a juvenile-approved facility.

In his order, Torres wrote that the government presented “clear and convincing evidence” that no release conditions could reasonably ensure public safety.

Hudson has pleaded not guilty to federal charges of first-degree murder and aggravated sexual abuse related to the death of Anna Kepner. His attorneys have not commented on the allegations.

The case is being prosecuted in federal court because Kepner’s death occurred in international waters, placing it outside the jurisdiction of any state. The incident took place aboard the Carnival Horizon in November while the ship was en route to Florida with Kepner’s family, including Hudson.

According to a criminal complaint, Kepner’s body was discovered hidden beneath a bed in a cabin she shared with Hudson and another teenager before the ship’s scheduled return. The official cause of death was determined to be mechanical asphyxia, indicating that breathing was obstructed by physical force or an object.

Minors are rarely tried in federal court, making Hudson’s prosecution under the adult system notable in the context of this case.