India, Nov. 25 -- The 18-year-old Anna Kepner's grandparents think they have lost two grandchildren: their granddaughter and her 16-year-old stepbrother, who is now being investigated for her death.

"No matter what we find out, no matter what they tell us, it's not going to bring either one of these children back," said grandmother Barbara Kepner.

Anna, from Titusville, Florida, was found dead on November 8 aboard the Carnival Horizon cruise ship, wrapped in a blanket and covered by life vests beneath a stateroom bed. According to the findings of the investigators, she died by asphyxiation caused by a "bar hold", an arm across the neck, and bruises on her neck lend weight to that possibility.

Court documents filed by Anna's stepmother,...