Life jackets designed to save lives could uncover the killer in the Florida teenager's cruise ship mystery.

 Life jackets designed to save lives could uncover the killer in the Florida teenager's cruise ship mystery.

Anna Kepner was found dead in a cabin on the Carnival Horizon cruise ship on November 7.

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They are supposed to be lifesavers, but in this case, they could at best point investigators to the killer.

According to a veteran detective who has followed the case, the life jackets that covered 18-year-old Anna Kepner's body when she was found dead two weeks ago by staff on the Carnival Horizon cruise ship could be crucial.

Pat Diaz, a former Miami-Dade County homicide detective and now a private investigator, said, "They will examine the life jackets, blankets, everything found in the room, and Anna's body."

And everything could hold important clues.

On Friday, ABC News reported that a preliminary investigation found evidence that Anna was strangled.

Fox News Digital has not independently verified this report. According to the Medical Examiner's Office, the official cause and manner of death have not yet been determined. However, a source familiar with the case said that toxicology and other lab testing have not yet been completed, but that bruises were found on the body.

But according to Diaz, if someone sweated during the murder, that person would have left DNA throughout the room, on the victim, and on any material used to cover the body.

As the FBI continues to investigate Kepner's mysterious death on a cruise ship, forensic experts say they are likely still analyzing DNA and other evidence to uncover clues that could indicate foul play.

Friday marks two weeks since the Navy sailor aspiring student was found dead in her cabin around 11 a.m. on November 7th.

After the ship returned to port the next day, her remains were transferred to the Miami-Dade County Medical Examiner's Office. However, the forensic pathologist in her case has not yet determined the cause and manner of death.

Diaz said it's still too early for toxicology and other lab testing results.

"They're doing DNA to match not only the 16-year-old boy, but also possibly trying to rule out the 14-year-old boy," he told Fox News Digital. "And nothing is happening quickly because whatever they find, they'll show to the grand jury."

Kepner was from a large, blended family with eight siblings.

No one has been charged with a crime in Kepner's death, but both parents of her 16-year-old half-brother said in court filings that the FBI is looking at him as a "suspect."

The FBI declined to comment, citing an active investigation.

But those close to Ana have accused the 16-year-old boy of inappropriate behavior, ranging from "climbing on her" while she was sleeping in the middle of the night to allegedly threatening her with a knife.

Speaking to reporters outside her memorial service Thursday night, her ex-boyfriend said he was on a FaceTime call with her at 3 a.m. while she was asleep. Then, he claims, he caught her stepbrother coming into the frame.

He said, "I was thinking, 'What are you doing in her room?'" "Then he got scared and ran, and I heard his footsteps in the house as he was caught."

Diaz said that if investigators are indeed considering him as a suspect, as her parents said, they will focus on evidence in the cabin.

The half-siblings were living in a room together, Anna's step-grandfather, Chris Donohue, previously told Fox News Digital.

Nicole Parker, a former FBI agent based in Miami who worked in the same office that investigated Kepner's death, said, "They're not going to rush this case." And they don't need to, because if the minor is truly a suspect, as her parents have claimed in court filings in a bitter custody battle, the risk of minors running away is low, Parker said.

"[Minors] can absolutely be charged, but the Federal Bureau of Prisons, they can't house minors," she said. "So, if I were to charge a minor, they would have to be placed in a special housing system. That's why sometimes the federal government gives it to local people."

However, she said that's unlikely to happen in a case of this magnitude.

"They could charge him at the federal level, and they could probably charge him as an adult," he said.