TITUSVILLE, Fla. — As the FBI investigates 18-year-old Anna Kepner’s mysterious death aboard a cruise ship, a custody battle involving her 16-year-old stepbrother has unveiled allegations of inappropriate behavior, family turmoil and disputed claims that underage drinking occurred in international waters.

No criminal charges have been announced, but her stepmother Shauntel Kepner’s ongoing legal fight with her ex-husband Thomas Hudson revealed Anna’s 16-year-old stepbrother has been eyed as a suspect.

Anna’s ex-boyfriend witnessed creepy interactions with the stepbrother visiting her bedroom at 3 a.m. FaceTime calls, a source close to the family told Fox News Digital.

“When I was on FaceTime with her, and she was lying down, and her brother tried to go on top of her,” the 15-year-old ex-boyfriend told reporters after Anna’s memorial service.

STEPMOTHER IN CRUISE SHIP DEATH MYSTERY FEARS CHILD COULD BE INCRIMINATED: COURT DOCS

He said he reported the encounter to Anna’s parents and said she had complained about being “uncomfortable” around her stepbrother before. He went on to describe Anna as his “first love” and said he would have been on the cruise with the Kepner family earlier this month if they hadn’t broken up.

“She was scared of him,” the ex’s father, Steven Westin, told Inside Edition separately. “Because he always carried around a big knife.”

WATCH: Anna Kepner’s ex-boyfriend breaks silence on her cruise ship death

After Anna’s death, the stepbrother’s father demanded a custody hearing, accusing his ex-wife of alienating their two youngest children from him after a violent altercation involving their oldest. He argued that his lack of involvement in their lives is having a serious impact on them.

The teen stepsiblings had access to alcohol in international waters despite being under 21, Hudson alleged at a hearing Thursday morning, according to Click Orlando, a local news site. Shauntel’s lawyer denied the claim.

FBI INVESTIGATES CARNIVAL CRUISE SHIP DEATH IN MARITIME MYSTERY THAT CAN BE ‘VERY COMPLEX,’ FORMER AGENT SAYS

Anna Kepner was identified by her family as the passenger who died onboard the Carnival Horizon. (Instagram/Anna Kepner)

“The [16-year-old]’s future has been put in jeopardy because of the choices made by [Shauntel],” according to Hudson’s filing.

Carnival requires that guests under 21 travel with someone 25 or older. Kids 14 and under have to be in the same or a connecting cabin. Teens 15 to 17 can be in a nearby stateroom, within about three cabins of the adult, and 18- to 20-year-olds can be booked anywhere on the ship as long as they’re linked to an adult over 25.

The teen’s current whereabouts are unclear. According to the filing, he has been released from custody and is staying with an unnamed third party.

Anna Kepner, her father, stepmother and several siblings in a family photo. (Shauntel Kepner/Facebook)

At some point during the course of the week, Anna’s obituary was also edited to change which family members were reflected.

The name of her dad’s second ex-wife, Tabitha Kepner, was removed entirely after initially being identified as her mother. The current version lists her mom as Heather Wright. A reference to the Donohue family was removed. So was a reference to her 16-year-old stepbrother, who is now believed to be the suspect.

Anna’s stepmother, Shauntel Kepner, formerly Shauntel Hudson, is her father’s current wife. In an emergency motion filed in Brevard County, she asked a judge to postpone a December hearing in a proceeding with her ex-husband due to the FBI investigation into Anna’s death aboard a Carnival cruise ship on Nov. 7.

“The Respondent (Shauntel) has been advised through discussions with FBI investigators and her attorneys, that a criminal case may be initiated against one of the minor children of this instant action,” her attorney, Millicent Athanason, wrote to a Brevard County judge on Nov. 17.

CRUISE SHIP DEATH: CHEERLEADER’S STEPMOM COULD BE FORCED TO TESTIFY AGAINST HER OWN SON

A still image shows 18-year-old Anna Kepner’s cryptic final TikTok post, posted eight days before she was found dead on a cruise ship. (@fl.anna18/TikTok)

Relatives say they have received few official answers since the ship docked. Anna’s birth mother, Heather Wright, told WESH 2 she learned of her daughter’s death through an online search. She has not responded to Fox News Digital’s attempts to reach her.

“I found out through Google. I ended up Googling it, because the only information I had was that my daughter was on a cruise,” she told the local outlet.

Similarly, Anna’s stepgrandfather, Christopher Donahue, 53, told Fox News Digital Wednesday that he too learned about her death through social media.

CRUISE SHIP DEATH MYSTERY: CHEERLEADER’S FINAL POSTS HINT AT HEARTBREAK AND RESILIENCE AS DAD BREAKS SILENCE

“I don’t know why Anna was staying in a room with her stepbrother,” Donahue said. He said he learned about the arrangement from a news article. 

“All I know is that she went on that boat, and she never came back,” he added. “You don’t go 0 to 100, but we weren’t on the boat. Everyone is heartbroken. There are questions. I don’t think we’ll ever know.”

READ THE FILING – APP USERS, CLICK HERE

The swirl of public claims around Anna’s death has revived long-simmering disputes. In a March 31, 2023, divorce petition filed in Brevard County and obtained by Fox News Digital, Anna’s former stepmother, Tabitha L. Kepner, alleges that Christopher Purcell Kepner, Anna’s father, had a “history of physical and mental abuse toward the minor children and toward the Petitioner,” and she sought sole parental responsibility for the children she shared with him and supervised time-sharing. 

She was married to Christopher Kepner after he split with Anna’s mother and before he met his third wife, Shauntel.

READ THE FILING – APP USERS, CLICK HERE

In 2024, Michelle Johnson filed a small claims suit in Brevard County against Shauntel Hudson seeking the return of several firearms, including a 12-gauge shotgun and two rifles, which she alleged Hudson refused to hand back.

The filings include a series of emails in which Johnson accused Hudson of “manipulating and alienating” her children from their father, describing the situation as “a very sad and heartbreaking ordeal.”

“Prior [sic] to you, manipulating controlling and brainwashing them for the past month,” Johnson wrote to Hudson. “It’s devastating and upsetting. Please step back and look at what’s the best for these kids? They need their family…”

That case was later dismissed after Johnson missed a service of process deadline.

Together, the records paint a portrait of a fractured family now thrust into the spotlight following Anna’s mysterious death aboard the six-day Carnival cruise.

Anna’s family and friends attended a service at The Grove Church in Titusville, Fla., on Thursday evening. One of the Kepners’ neighbors told Fox News Digital Thursday that their street has been quiet since Anna’s death. He described the Kepners as a friendly family.

Two vehicles, a Dodge truck and Chevy SUV, were parked in the Kepners’ driveway, but no one answered the door. Investigators have not disclosed a cause or manner of death, and prosecutors have not filed charges.

Anna Kepner’s family said she had dreams of joining the military. (Instagram/Anna Kepner)

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Hundreds of mourners gathered Thursday at The Grove Church in Titusville, Florida, to celebrate the life of Kepner. Guests were greeted by her graduation photos and invited to leave a fingerprint on a poster bearing her picture. Inside the church’s auditorium, a slideshow traced her life through images of karate lessons, Disney trips, lake days, beach outings, cheerleading fundraisers, and carefree flips at a bounce house.