“I need you to call me asap it’s an emergency.”

That was the message Shauntel Kepner sent to her ex-husband, Thomas Hudson, at 7:30 p.m. on Nov. 8 — with a subject line that said “Emergency,” according to evidence filed in the divorced couple’s ongoing custody dispute and obtained by PEOPLE.

One day prior, the lifeless body of Shauntel’s 18-year-old stepdaughter Anna Kepner was discovered in her cabin aboard the Carnival Horizon by a maid.

Hudson said in a court filing that “[he and Shauntel’s] oldest minor child is a suspect in the death of [Anna] that occurred on that cruise.”

What is unclear, however, is why 32 hours elapsed before Shauntel told her ex-husband that her stepdaughter had died.

Hudson also submitted into evidence an exchange with Shauntel about their 16-year-old son, who, as suspicion swirls around him, has been living with a family member at an undisclosed location.

During a terse exchange about Shauntel’s decision to cancel a visit between Hudson and his youngest daughter, Hudson wrote: “I kept my mouth shut when you told me that you can’t jeopardize your marriage for helping [redacted] your son.”

Shauntel’s current husband is Christopher Kepner, the father of Anna.

Shauntel’s lawyer said at a Dec. 5 custody hearing that Shauntel and Christopher sent her teenage son to live with a relative in order to remove “any risk of any danger to any of the other children in the home.”

At that same hearing, Shauntel testified that Anna, her stepbrother, and her 14-year-old half-brother were the closest of friends — and said the trio shared a room on the Carnival Horizon cruise ship from Nov. 2 to Nov. 9.

That cabin is where Anna “was found asphyxiated under the bed,” according to a court filing obtained by PEOPLE.

It has now been close to six weeks since Anna’s death, and neither state nor federal prosecutors have filed charges.

At the Dec. 5 custody hearing, Shauntel’s attorney, Millicent Athanason, strongly suggested that charges would be filed soon. She said the delay was because the FBI was determining whether to turn over the evidence in the case to state or local authorities. When asked to confirm this, an FBI spokesperson declined to comment to PEOPLE.

In his own filing ahead of their Dec. 17 court hearing — which was continued — Hudson wrote that their son is “currently under investigation by the Federal Bureau of Investigation for a federal crime.”

PEOPLE obtained documents confirming that the teenager is staying with a third party who holds power of attorney, and can only be relocated with the consent of both parents. The documents also state that his location is known only to Shauntel, Hudson and law enforcement.

Lawyers for Shauntel and Hudson did not respond to PEOPLE’s request for comment.