The death of 18-year-old Florida cheerleader Anna Kepner, whose body was found concealed under a bed on a Carnival cruise ship, has been officially ruled a homicide, according to her death certificate released to her family and shared with ABC News.

The document states that she “was mechanically asphyxiated by other person(s)” and lists Nov. 6 as the date of injury.

Kepner was found dead on Nov. 7 aboard the Carnival Horizon while on a vacation with her grandparents, stepmother, father, siblings and stepsiblings. She was located wrapped in a blanket and covered with life jackets, placed under the bed in the stateroom she shared with her 16-year-old stepbrother and younger brother.

Forensic experts described “mechanical asphyxia” as a condition where something external prevents a person from breathing.

A board-certified pathologist, Dr. Priya Banerjee, explained to media outlets that this type of asphyxia usually restricts the chest or abdomen, making it impossible to breathe.

Former New York City chief medical examiner Dr. Michael Baden said that although mechanical asphyxiation is not always homicide, it can be, and prosecutors would ultimately decide on any charges.

The FBI is leading the case and has not announced any suspects publicly. However, court filings in a separate family matter identified Kepner’s 16-year-old stepbrother as a possible suspect. No arrests have been made.

The death certificate lists her time of death as 11:17 a.m. on Nov. 7, but it says the fatal injury occurred the night before, Nov. 6, the last time she was seen alive. A security source briefed on the internal investigation said the teenager was found stuffed under the bed during room cleaning.

Her 14-year-old brother reportedly told investigators he overheard yelling and sounds like chairs being thrown in the room while Kepner and the stepbrother were alone. He later slept in the same cabin, unaware that his sister’s body was hidden a few feet away.

Kepner’s ex-boyfriend, Joshua Westin, said through media reports that Anna had told him she did not feel safe around her stepbrother.

Westin claimed she had mentioned incidents of sexual harassment and described what she believed was an unhealthy obsession from him. He said she did not report it earlier because she feared he might harm her.

Westin’s father also alleged that the stepbrother often carried a “big knife,” a claim raised during media interviews.

The teen’s grandparents said she was an independent young woman preparing to graduate high school in May. They told ABC News they had looked forward to watching her pursue her dream of joining the U.S. Navy and later becoming a K-9 police officer.

A formal autopsy and toxicology report have not been made public. Investigators have not confirmed earlier mentions of a possible “bar hold” or neck restraint, although the family said they were informed of asphyxiation during early FBI updates.

As of Monday evening, federal authorities had not commented on any potential charges. Attorneys for the stepbrother’s parents have not responded to requests for comment.

References: foxnews, abcnews