Anna Kepner's Grandparents Speak Out About Stepbrother After Cruise Ship Death

Anna Kepner’s grandparents are shutting down any talk she was scared of her stepbrother -- the teen reportedly under investigation in her cruise-ship death -- making it clear they have faith in his innocence.

In an ABC News sit-down interview, Barbara and Jeffrey Kepner said 18-year-old Anna and her 16-year-old stepbrother were "two peas in a pod," and cared for each other "in the right way" -- a far cry from what Joshua Tew, Anna’s first love, claimed ... saying her other brother told him about a nasty blowout the pair allegedly had inside the cabin they were all sharing.

The grandparents say authorities told them the stepbrother is considered a suspect in the case. They admit they’ve got no clue what actually went down inside that cabin -- they’re waiting on answers just like everyone else -- but pointing the finger at the stepbrother? They’re nowhere near ready to go there.

The family says this cruise was meant to kick off a new tradition -- a big, blended-family getaway -- and they vividly remember the last night they saw Anna. Her braces were bugging her at dinner, but she powered through, stayed for the fun ... then headed back to her room.

As you know, the cheerleader’s body was found in that shared cabin on Nov. 8, reportedly wrapped in a blanket and tucked under a bed ... as we reported, she died from asphyxiation reportedly caused by a "bar hold," basically someone’s arm pressed across her neck. She’s not believed to have been sexually assaulted.