Anna Kepner, the teen found mysteriously dead on a Carnival cruise ship earlier this month, and the stepbrother reportedly suspected in her death were like “two peas in a pod,” her grandma said Monday.

The 18-year-old Florida high school senior had been traveling on the Carnival Horizon ship with members of her blended family when her corpse was found stashed under a bed — wrapped in a blanket and covered with life jackets.

Authorities have not confirmed who may have been behind her death, but court documents from an unrelated case have indicated that Kepner’s unidentified 16-year-old stepbrother, who was sharing a room with the teen at the time, is being eyed as a suspect.

Kepner’s grandmother, Barbara Kepner, said in an interview with ABC News that authorities told the family the stepbrother was the only person seen going in and out of the room before the grim discovery was made Nov. 8.

But Barbara insisted the stepsiblings cared for each other and were “just like brother and sister.

“I know that those two kids cared about each other in the right way,” the grandmother said.

On the family trip were Anna; her grandparents; their son, Anna’s dad; his wife; Anna’s 14-year-old brother, the stepbrother, and her younger sister and stepsister, reports have said.

“The two younger girls stayed with the parents, and then the three teenagers, they decided amongst themselves they wanted to stay in the room together,” the grandmother said. “But we had a larger room, and we made it very clear that at any time if they weren’t getting along, they didn’t want to be together, we had an extra bed in our room that they could come to.

“I can’t accuse him because I don’t know what happened in that room,” Barbara added of the stepbrother.

She said he later told her “in his own words” that he doesn’t recall what happened on the ship.

“I believe, to him, that is his truth,” the grandmother said. “He was an emotional mess. He couldn’t even speak. He couldn’t believe what had happened.”

After the cruise ship docked, Anna’s stepbrother was hospitalized for psychiatric observation and later released to a family member.

The results of the cheerleader’s autopsy are still pending, but sources said she likely died from asphyxiation. There were no apparent signs of sexual assault, nor were there drugs or alcohol in the girl’s system, according to sources.

It previously emerged that Anna’s stepbrother allegedly had a creepy obsession with the teen and relentlessly pursued a relationship with her — and was once even caught climbing on top of her while she slept.

“She was scared of him because he always carried around a big knife,” the father of Anna’s ex-boyfriend, Joshua, told “Inside Edition.”

“He’s like infatuated, attracted to her like crazy. He always wanted to date her.”

Anna’s ex tried to warn the girl’s parents, but they apparently didn’t believe the concerned teen, the man claimed.

The developments were laid bare in court last week during an unrelated custody matter tied to the divorce of Anna’s stepmother and her ex-husband.

Anna’s stepmother, Shauntel Hudson, and her ex-husband are involved in a bitter custody battle over their two kids, who Hudson claimed were physically abused by their father.