When a woman falls to her death while hiking with her husband in Rocky Mountain National Park, rangers question if her death was an accident or a heinous act of violence.

They were two beautiful families living out their dreams, but gunshots in a parking lot revealed an ugly truth. Investigators uncovered three lives tangled in a love triangle. There were many secrets, but which one was the key to solving the mystery?

Deede Keller had a loving family, a tight circle of friends and a new man in her life. When she vanished, disturbing clues would point investigators to a suspect with a dark secret. The case provided a twist that left the courtroom astonished.

Keith Bryan was a beloved fire chief, a pillar of his community. Then he was shot in his home, leaving police to wonder who would want to hurt the local hero? Turns out, someone was living a secret life, and it was about to be exposed.

Diana Lovejoy and her husband welcomed a baby boy, but then, their marriage crumbled. A bitter custody battle followed. Fearing for her safety, Diane turned to a man skilled in self-defense but, it turns out, someone else was in grave danger.

Police believed a pair of double homicides in Nebraska, five years apart, might be connected. Investigators working to solve the crimes feared the killer might strike again. Could they catch him in time?

Kay Mortensen took pride in preparing for every threat, so when he was found dead at home, those who knew him were stunned. The killing put two of Kay's loved ones behind bars and in danger.

After a house fire in suburban New Jersey, investigators discover a twisted love triangle filled with jealously, love and murder.

Annie Kasprzak has a second chance at a happy life after being adopted by her case worker. Then, the 15-year-old vanishes. Her parents find a note in her room that reveals a secret Annie has been hiding.

For many, the holiday season is filled with joy but, for the Jennings family, the night before Christmas became a waking nightmare. A gunshot rang out and investigators had to unravel whether a secret lead to a tragic suicide or if this was murder.

A group of adventurous Americans thought they had found paradise. It was a tropical hideaway, the kind of place where people didn't ask a lot of questions about their neighbors, until some of those neighbors started to disappear.

For a group of stage actors, life seemed to be imitating art in the worst way when a young college student was killed. Police believed they knew who was responsible, but this mystery had a grand finale no one saw coming.

He dreamed of being the next Steve Jobs, a young entrepreneur who wanted to change the world. But his world came crashing down one morning with four gunshots. This was a crime of passion: a fatal triangle involving a husband, a wife and a boss.

A quiet night was shattered when intruders terrorized a Florida couple and their young son, killing one of them. Investigators questioned the initial story. Then, a tip led them to another family with dark secrets, and that's when bonds were tested.

Nona Dirksmeyer was a young beauty queen with a boyfriend she adored. They were planning a future together. Then, Nona was brutally killed. The crime shook her hometown and exposed someone with a secret past. But did the evidence add up to murder?

Craig and Laura Rideout appeared happy but, after a contentious separation revealed an ugly secret, one of them would soon be dead. Clues pointed to four possible killers and left investigators wondering if this murder was all in the family.

What happened in Cara Ryan's bedroom was a mystery. She admitted she shot her ex-husband, but investigators needed to know if it was murder or self-defense. Detectives heard several versions of the story, but for a jury, there was only one truth.

When a captivating, sweet nurtured single mom was found dead in her garage, detectives in Frisco, Texas uncovered a series of potential suspects, all of them connected in different ways to her complicated and secretive life.

It was an unthinkable crime. Brittany Eldridge was nearly nine months pregnant when she was found dead in her apartment. Investigators focused on two men with possible motives.

When a woman reappeared just two days after her boyfriend reported her abducted, police accused a couple of perpetrating a hoax. When another similar crime takes place, police decide to re-examine the case and find an unlikely suspect.

It was Friday the 13th and something sinister was about to happen: a chilling double murder in an upscale home. The evidence seemed to tell a clear story. Then investigators discovered a marriage filled with secrets and a story that didn't add up.

Jodi Arias and Travis Alexander had chemistry right from the start. Then he was killed, and she was arrested. The trial riveted millions, exposing Jodi's secrets. Yet, it did not solve one mystery: exactly who was this woman behind the veil of lies?

For a day that ended so tragically, it started with roses. Nathan and Denise Leuthold had known each other since grade school. Together they built their family on faith, but in a flash, one of them was dead and the other was under suspicion.

After a house fire in suburban New Jersey, investigators discover a twisted love triangle filled with jealously, love and murder.