Teen's Death on Carnival Cruise Ship Ruled a Homicide

The teenager who died under mysterious circumstances on cruise ship Carnival Horizon earlier this month was killed by asphyxiation, and her death has been ruled a homicide, according to a death certificate released by her family. A medical examiner in Miami concluded that Anna Kepner, 18, "was mechanically asphyxiated by other person(s)" at about 1117 hours on November 7. The document confirms previously-reported preliminary conclusions of FBI investigators.

Kepner was a straight-A student, a varsity cheerleader, and had planned to enlist in the military after graduation, according to her family.

A security source has informed ABC News that Kepner's body was discovered underneath a bed, concealed with a blanket and life vests. The body was discovered on November 7 by a crewmember who was cleaning Kepner's cabin, Florida Today reported.

The FBI is investigating the case under "special maritime jurisdiction," which applies when specific criteria about the vessel, the victim or the voyage are met. Carnival Cruise Line is fully cooperating in the inquiry.

Kepner's stepbrother - who was co-occupying the cabin with her, Kepner's grandmother told ABC - could face charges in connection with the death, according to court documents from an unrelated child-custody case. No arrests or charges have yet been made.

In a memorial earlier this month, Kepner's friends and associates remembered her for her positive outlook and her involvement in her community. "When she walked into a room, she would light it up. If you were sad, she’d make you laugh. She would joke around and be the funniest little person in school," Kepner's parents told ABC News.