Heidi Allen was working at a store to earn cash for college and was last seen there when she vanished. A man was convicted of murdering her, but years later someone else confessed to friends that he did it, blowing the old case wide open.

Corey Parker had plenty of admirers, but maybe one of them liked her too much. Her murder jolted a sleepy seaside community with the chilling realization that a killer was walking among them.

Fences make good neighbors, but this one triggered a deadly fight. Only two men were there and the man who shot first told investigators his story. However, the crime scene was telling another story.

She yearned to make it in Hollywood. Instead, Brittany Tavar made headlines when she vanished. Investigators had plenty of leads – a handsome boarder, the friend turned enemy, or they wondered if the free spirit could have left on her own.

Realtor Lindsay Buziak thought she'd landed dream clients when a mystery couple said they wanted to buy a million-dollar home. What seemed like a golden opportunity turned deadly when Lindsay was murdered in the ritzy home.

They were a couple who seemed made for each other. Seemona Sumasar thought she had met Mr. Right, but her instincts proved wrong. Nothing was as it seemed.

In a suburb of Toronto, a family lives in fear as one relative after another is found dead over the years in the same house.

It was a mystery from day one: A young father’s life cut short. Matt Podolak's death was puzzling. The word poison kept coming up. Matt’s brother embarks on a long quest for the truth.

Uncovered pages from John Hinckley Jr.’s diary are revealed. Hinckley began writing after he was arrested for trying to assassinate President Ronald Reagan.

Two Tulsa brothers fight for more than 20 years to prove their innocence, after they were wrongfully convicted for separate murders;

Lester Holt spends two nights locked up and embedded inside the largest maximum-security prison in America.

Before the Menendez brothers, the Bobbitts or even O.J., Pamela Smart was television’s first true-crime fascination. Smart’s husband was found murdered and when police began to investigate, they discovered that she was keeping a big secret.

Rod Covlin calls 911 after his young daughter finds his estranged wife unconscious in the bathtub. Soon after her mysterious death, family members would come to suspect what happened was no accident.

When college student MacKenzie Lueck vanished from a park in Salt Lake City, her friends were dedicated to finding answers. The search made national headlines and the investigation revealed a secret that stunned even her closest friends.

Police are perplexed when they find the body of a young woman but are unable identify her; with the help of amateur investigators and new DNA technology, a dogged investigator finds her killer and her identity.

Two tenacious sisters are determined to fulfill a promise to investigate the mystery surrounding their mother's death.

When a model and up-and-coming YouTube celebrity is found dead in their pool, police question her husband see if he can provide any answers.

This is the behind-the-scenes story of Rebecca Musser vs. Warren Jeffs, one of the FBI’s most notorious fugitives. Rebecca opens up about life in the Fundamentalist Church of Jesus Christ of Latter-Day Saints and why she decided to leave.

Gianni Versace’s longtime partner Antonio D’Amico speaks about the murder of the fashion icon. Versace’s murder came amid a months-long manhunt for Andrew Cunanan, who was accused of committing four other murders throughout the US in 1997.

Linda Watson is a single mom raising a beautiful daughter when she disappears; then, suddenly, Linda's mom goes missing too, along with another friend; police are convinced the three cases are connected, but unraveling the mystery takes years.

She was an A-lister in a town famous for glitzy ski resorts and celebrities; when socialite Nancy Phister was murdered, the news reverberated around Aspen; Nancy had a long list of friends, but she also had enemies.

Friends think something isn't right after the mysterious disappearance of a Colorado rancher and spend years fighting for answers.

Two years after the disappearance of his wife, Josh Powell kills his two sons and himself. Watch Josh's last in-depth TV interview. Plus, a 911 dispatcher discusses the emergency call placed by a social worker.

She was a small-town girl from rural Wisconsin; he was a Chicago superstar, a hometown hero with the legendary Bears; together, they were expecting their first child, but no one was expecting their tale to end in the deadly way that it did.

A young woman is abducted in Ecuador, and as her family and investigators race to save her, she plots to save herself; her daring plan involves a little something hidden at the bottom of her bag, but time is running out.

A small-town girl moves to Las Vegas, where she finds a new career and new love; soon after, however, she vanishes, and within days, police find her body; finding who killed her will be a tougher mystery to crack.

It is common for long-haul truck driver Lloyd Ford to be gone for stretches, and when he disappears, it doesn't raise many flags; at least two people know where he is, and they guard the secret for 27 years, but the truth is about to be revealed.

Brooke Wilberger was 19 when she was kidnapped; her family begged for her return, but months passed before police got their first break, a similar attack more than 1,000 miles away.

The murder of a young businessman in the Old San Juan district of Puerto Rico marks the start of a 15-year-long hunt to find the killer.

When hikers find a 21-year-old UCLA student's body in a Los Angeles-area train tunnel, detectives wonder if his interest in an alternative religion is connected to his murder.

Details expose how the Gucci family was undone by jealousy, backstabbing and, ultimately, an act of murder; insiders close to the fashion empire speak out about the murder of a prominent family member.