Amanda Antoni was found dead in her basement. No one can figure out how or why she died.

It was a chilly October afternoon in 2015 when Lee Antoni returned to his Calgary, Alberta home after a weekend away. Upon his arrival, he found a gruesome scene — his wife, 31-year-old Amanda Antoni, was dead, lying in a pool of her own blood at the bottom of their basement stairs.

It quickly became a case that would baffle investigators, and what followed was an investigation that would ultimately leave people with more questions than answers.

Now, the the case has been revisited by Netflix's popular true crime series, Unsolved Mysteries — and remains as baffling today as ever.

Watch the trailer for Unsolved Mysteries: Volume 4. Article continues below.

What happened to Amanda Antoni?

When police arrived at the Antoni residence on October 26, 2015, they were confronted with a scene that even seasoned detectives found disturbing.

Amanda's body was at the bottom of the basement stairs, and she had suffered severe head trauma. The amount of blood at the scene was shocking, and prompted immediate suspicions of foul play, with Staff Sergeant Sean Gregson of the Calgary police homicide unit describing it as one of the bloodiest crime scenes he'd ever encountered.

It seemed obvious, at first — Amanda had to have died by homicide.

As detectives began to investigate, they found several details that they felt supported the case for Amanda's death being the result of a homicide.

For starters, Amanda had last been heard from on Saturday evening, nearly two days before her body was discovered.

Detectives felt that this painted a picture of a potential struggle, but as the investigation progressed, things became less clear-cut.

In a twist that left investigators second-guessing their initial assessment of the scene, forensic evidence seemed to contradict the initial homicide theory. You see, all the DNA, footprints, and fingerprints at the scene belonged solely to Amanda.

There was also no sign of forced entry, and no evidence that anyone else had been in the house. Even more perplexing? Amanda's own footprints were in the blood, suggesting that she had moved around and even stood up at some point after her injury.

The question was: if she was able to move, why didn't she try to go upstairs and call for help?

Theories and speculations.

As the investigation continued, several theories emerged:

Amanda suffered an accidental fall.

Some investigators suggested that Amanda might have fallen down the stairs, possibly hitting her head on the ceramic piggy bank in the process.

This could explain the severe head trauma and the lack of evidence pointing to an intruder.

Amanda had suffered a medical emergency.

Another theory suggested that Amanda might have suffered an unexpected medical event like a seizure or stroke, which could have caused her to fall and sustain the fatal injuries.

Amanda had died as a result of foul play.

Despite the lack of forensic evidence, some still believe that Amanda's death was the result of foul play.

The overturned chair and the position of her phone in the hallway have been cited as potential signs of a struggle.

So how did Amanda Antoni really die?

After 14 months of intensive investigation, Calgary police made a surprising announcement: Amanda Antoni's death was ruled accidental, with detectives citing the lack of evidence to support a homicide ruling, and the inability to definitively prove that anyone else was involved.

However, the ruling has done little to stop the questions surrounding the case. Members of Amanda's family, in particular, have found it difficult to accept that Amanda's death was an accident, and believe that there are still too many unknowns about what happened that day.

In 2024, Amanda's case gained renewed interest when it was featured on Netflix's Unsolved Mysteries. The episode, titled Body in the Basement, brought the story of her death to a global audience.

Recently, Terry Dunn Meurer, co-creator of Unsolved Mysteries, shared her thoughts on the case.

"Body in the Basement is probably some weird, strange, bizarre accident. I don't know how solvable that is," she said.

"Somebody would have to come forward and say that they had attacked her in her house. And I don't know that that's going to happen. I just don't know if it was a stranger attack, an assault. It would be such a random crime."

Meurer went on to highlight the uniqueness of Amanda's case, noting that it's rare for an investigation to start as a homicide and then shift towards an accidental death theory.

"I think for me what was so interesting in that case was following Dave Sweet, the detective, following his thought process through that whole case. It's rare. It was such a clear-cut homicide. And then when the DNA comes back from all the blood in the basement and it's only Amanda's blood, Dave started to rethink everything and thought, 'could this be an accident?'"

The search for answers continues.

Nearly a decade on, Amanda's case remains a source of fascination and frustration for many.

Still, Staff Sgt. Sean Gregson expressed hope that the Unsolved Mysteries episode might generate new leads or information.

Meanwhile, for Amanda's family and friends, the search for closure continues as they reckon with the case's many lingering questions: How did she sustain such severe injuries? Why didn't she call for help? Was someone else involved?

As the case stands today, Amanda Antoni's death serves as a haunting reminder that sometimes, even with modern forensic techniques and thorough investigations, the truth can remain elusive.

Unsolved Mysteries is streaming now on Netflix.

Feature Image: Netflix.