A love triangle leads to years of stalking, property destruction, threats, and murder.

When a mother of four dies unexpectedly on Valentine's Day, her death is attributed to natural causes, but a detective suspects that someone murdered the woman.

When a model and up-and-coming YouTube celebrity turns up dead, police question her husband in the hope he can shed some light on the situation.

As a murder victim's sisters dedicate themselves to finding the killer, an unexpected source turns the case upside down.

A community comes together to search for a young woman who goes missing from a Halloween party.

A young father's murder at work leads investigators to deep secrets about sex, friendship, religion and family.

Author Rachel Jeffs talks about what it was like to grow up as the daughter of the self-proclaimed prophet of the Fundamentalist Church of Jesus Christ of Latter-Day Saints, Warren Jeffs.

An investigation of a woman found murdered in Fort Worth, Texas.

An anonymous letter leads authorities investigating the poisoning death of a chiropractor to an unlikely suspect.

A small-business owner and his bride are murdered shortly after their wedding; police suspect a family feud is the cause.

A look at the case of con man John Meehan, including interviews with his wife and her daughter, his ex-wife, law enforcement officers, and the Los Angeles Times reporter who shined a spotlight on the story.

A couple's anniversary celebration ends in murder during what appears to have been a home invasion, but investigators believe the suspect might be connected to the victim.

Brandy Daniels believed someone was stalking her. Then, the single mother was found slumped over in her car, shot dead. Investigators would spend years navigating the twists and turns searching for her killer.

A murder outside Pleasantville, Iowa, divides a family and forces one man to take the investigation into his own hands.

When a young mother disappears after leaving her infant in the care of her local pastor and his wife, Florida detectives search for her for five years, uncovering a web of secrets and lies.

When a young Army medic based at Ft. Bragg, N.C., goes missing, police can't solve the case despite having a suspect until an unorthodox private investigator steps in to help.

A former marine who once was the hero for a woman in an abusive marriage may have let his desire to help go too far.

A woman's death is initially ruled a suicide, but when a new investigation begins, police begin to suspect murder.

When dozens of homeowners find themselves on a Napa Valley hilltop surrounded by fire, two teams of daring chopper pilots risk their lives in a mission to rescue them.

When a complicated Texas love triangle ends in murder, a pink gun leads to an arrest, until new evidence prompts investigators to rethink the case.

Former DEA agent Andrew Hogan details his search for Mexican drug lord Joaquín "El Chapo" Guzmán with never-before-seen videos and photographs.

When a young Florida law professor is shot, baffling his family, friends and police, a complicated investigation leads police to a surprising theory of the crime; the victim's family speaks out for the first time.

Four families that barely escaped the catastrophic Montecito, Calif., mudslides alive, and the rescuers who risked their own lives to help.

A bizarre cyber-revenge case lands a young woman in jail; an unexpected twist reveals the real culprit.

A Tennessee resident is murdered in her bedroom; investigators have little evidence and struggle to find answers.

Former USA Gymnastics national team coordinators Bela and Martha Karolyi talk with Savannah Guthrie about the Olympic sex abuse scandal; Olympic gold medalist McKayla Maroney describes the sexual assault she endured.

The disappearance of a young woman from Bend, Ore., leads to an intense manhunt after the suspect embarks on a two state crime spree.

When one woman breaks off her relationship with a boyfriend she says abused and stalked her, he moves on to something even worse.

After a 15-year-old girl disappears, investigators discover a creek where the local teenagers hang out that may hold the answer to her disappearance.

Rapper Meek Mill interview; exploring controversies surrounding the criminal justice system, including the parole system, wrongful convictions, challenges faced by law enforcement, alleged police abuse and more.

When a young woman is found dead in a field on the outskirts of Green Bay, Wis., a fitness tracker helps detectives solve the mystery.

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.

A look at the future of marijuana in the United States, including state-of-the-art science and interviews with patients, their families, leading scientists, doctors, federal legislators and a former professional football player.

Interview with Andrea Constand, the first woman to pursue charges against Bill Cosby, and four other Cosby accusers who testified against him.

Sixteen parents fighting to end college hazing at fraternities speak out together for the first time; cases of alleged hazing at various universities.

A recent law school graduate in Georgia who has a promising future disappears without a trace.

A father in Hawaii tackles setback after setback in his fight for justice for his murdered daughter.

A woman's DNA test sends her father halfway around the world to confront his past.

When a prominent attorney claims to have accidentally shot his wealthy wife, the local prosecutor questions his story.

The reality of life along the U.S.-Mexico border, including interviews with families seeking asylum, news on the controversial policy of separating migrant families, and fact checks on claims made by both political parties.

A woman whose ex-husband killed six people in Arizona, allegedly targeting individuals with connections to their divorce; interviews with experts on the topics of domestic violence and mass murder.

A husband convicted of murdering his wife is granted parole; others fear he may kill again.

An in-depth look at the journalists who exposed the dangers of cult leader Reverend Jim Jones; interviews with witnesses to murders carried out by Jones' followers.

A popular high school student is found murdered in her bed; two students help police solve the case.

When two mothers meet after one of their sons disappears after a college party, their search for answers leads them down an unexpected path.