A suspicious death, a bloody axe and a heated argument: The Mystery at Mile Marker 45.

This post mentions suicide and could be triggering for some readers.

The new season of Unsolved Mysteries has dropped on Netflix, leaving people around the world talking about the case of Tiffany Valiante, which featured in episode one, Mystery at Mile Marker 45.

The case follows how 18-year-old Valiante came to be found dead on a train track not long after she graduated high school. While the death was almost immediately ruled a suicide, her parents are continuing to fight back on the ruling.

As the story grips the world, online sleuths have been able to share more details surrounding Valiante’s death, including a few details that were left out of the show.

Here’s everything we know about the mysterious death.

What happened to Tiffany Valiante?

Tiffany Valiante was celebrating her high school graduation on July 12, 2015.

It seems she was at a party with some friends before coming home to her parents, whom she argued with at approximately 9:30pm, leading her to walk out of the house. Many have said even this move was strange, given Valiante hated the dark.

A CCTV image shows her walking away from home, wearing a t-shirt, shorts, trainers and a headband. It was the last time she was seen alive.

Not long after she walked from the house, Valiante’s parents realised no one knew her whereabouts, and began to worry. They found her phone lying in the grass outside their house.

The following morning, Valiante was found on a train track. She was only partially clothed, and was barefoot. According to the New Jersey Transit Police, who investigated her death, as well as the medical examiner’s office, she was hit by a train.

The death was ruled a suicide, but Tiffany’s parents refuse to believe she took her own life.

"I was devastated. I couldn't understand how they could come up with that. My daughter wasn't depressed. She wasn't suicidal. Tiffany was happy,” her mother, Dianne Valiante, told the show.

"She was making plans to go to college, she was making plans with her roommate, she was making plans to play softball that Wednesday. She had plans to go to Great Adventure the next morning with friends."

CCTV footage of Tiffany Valiante the last time she was seen alive. Image: Netflix. 

Not a suicide?

With this in mind, Valiante’s parents began to believe she had been murdered, and began to work with a series of private investigators to see if they could find out what happened to their daughter.

However, they ran into a series of issues. No family members or friends had been interviewed about the death, and there had been no psychological autopsy or rape kit carried out, and Valiante’s body had been cremated by the time they realised how little evidence was available.

Evidence at the scene had been left behind or stored poorly, with some of it becoming mouldy and impossible to test for DNA.

It’s believed the evening she died, Valiante had been using a friend’s debit card, a situation that had led to an argument with her parents that saw her leave the house.

The theory has been floated that she then got into a car willingly, with headlights visible in the final CCTV image of Valiante.

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What Unsolved Mysteries told us.

Unsolved Mysteries brought some pretty convincing evidence to light, convincing the audience that Valiante’s suicide was unlikely.

Firstly, she was found wearing only underwear. When Valiante’s parents last saw her - and in the CCTV image - she’s fully clothed.

Valiante’s headband and trainers were found about two miles from where her body was discovered, but her t-shirt and her shorts have never been found.

It was also found that Valiante’s feet were uninjured. Given she was found two miles from where her shoes were, it was theorised that she walked the two miles to the train tracks to end her life. However, the path between locations was full of jagged rocks and broken glass, and Valiante’s feet showed no sign of any harm. This supports a theory floated by one of the investigators, that maybe she was killed and then placed on the tracks by her murderer.

There were initially two eyewitnesses to Valiante’s death - a student engineer and a senior engineer who were both on the train that hit Valiante. They both claimed to see her jump in front of the train, but later, under oath, their stories changed. They said they both had their back to the front of the train, and hadn’t seen her at all. Later on, the story would change again, with the student engineer claiming he did see Valiante jump in front of the train.

However, the inconsistencies could come down to shock, as noted in the show by independent medical examiner H. Louise Houseman. The ‘jumping’ could have also been mistaken for the way Valiante’s body might have been thrown upward on impact.

Tiffany Valiante. Image: Netflix. 

What Unsolved Mysteries left out.

Unsolved Mysteries did not report the New Jersey Transit Police might have lost a potential murder weapon.

According to NJ.com, a photo of an axe with “red markings” was found and photographed at the scene. Valiante’s parents only saw it after winning a court order to get evidence tested, and by then, it had been misplaced.

The documentary also left out that Valiante allegedly stole money from her parents a few months before she died, a fact that might have been connected to her use of her friend’s debit card the same night she died.

The theory pointing to murder.

Valiante’s parents still do not believe their daughter died by suicide, and seem hopeful that answers can still come to light.

While no details can be confirmed, the investigators working with Mr and Mrs Valiante seem to believe that after the argument, Tiffany got into a car, likely driven by someone she knew, was murdered, and then placed on the tracks some time after.

For now, the death remains ruled a suicide, and private investigations are ongoing.

Unsolved Mysteries is streaming on Netflix. 

If you think you may be experiencing depression or another mental health problem, please contact your general practitioner. If you're based in Australia, 24-hour support is available through Lifeline on 13 11 14 or beyondblue on 1300 22 4636.